I'll briefly explain certain terms that I use that others may not, just so the information I provide is as clear as possible.

Trash - The weakest, most numerous zeds. Anything including and weaker than gorefiends, I consider trash.
Mid size zeds - Sirens, bloats, husks, rioters, and EDARs. These are all zeds that have generally more health than trash, and are all have very dangerous close range attacks. These are still not difficult to fight 1v1 but in a greater wave or when fighting multiple, they can become exponentially more dangerous. EDARs are a little different because their central crit spot is extremely vulnerable to perks that fire bullets, but almost useless to those that don't. Quarter pounds also are closer to being mid size zeds, but are the most dangerous within that category.
Big zeds - Refers to fleshpounds and scrakes, but you can think of the boss as being one as well. Best met with specialized perks and focus fire.

Stun Vs. Knockdown Vs. Reaction - A knocked down zed will actually ragdoll and fall over onto the ground, before getting back up. A stunned zed will stand upright in a fixed position for a short amount of time. "Reaction" is the game's word for when zeds stumble or are otherwise jostled from a powerful attack. When you fire a grenade launcher at a rioter and they duck to the side to dodge the grenade, this is considered a "reaction" response from them.

Passive bonuses - Every perk has a few percentage-based bonuses that increase with level, and some have unique gameplay mechanics that you will always have regardless of your skill choices. Things like the damage bonus of every perk, increasing mag size of the SWAT, or ammo backpack from the Support are all passive bonuses.

High or Low player count games - Not set in stone, more of an influence in suicidal difficulty or higher. I consider 4 players total high player count, and 3 and under low player count. Player count affects health of individual zeds and total zeds per wave, the biggest change being big zeds being exponentially harder to kill. 3-4 players is the rough threshold where specialized roles become more important.

Higher or lower difficulty - The biggest difficulty gap by far is between hard and suicidal. In suicidal, all zed attacks will be used and damage taken will be far greater. Poor loadouts and strats are far less likely to work in multiplayer games and some perks missing crucial skills will be nearly useless. "Lower difficulty" refers to hard and normal; "Higher difficulty" refers to suicidal and hell on earth.

Damage thresholds - A damage threshold is a change in how many bullets it takes to kill something. You never see exact health or damage numbers in game, you instead will notice how many shots it takes to kill something. Skills and damage bonuses are not useful because "I now do X amount of damage per second" but instead because "I can now kill X zed with one shot instead of two." More important with lower ammo count weapons, but something to think about for any weapon.

Weapon types and terminology -
Fully automatic: fires continuously with the trigger held.
Semi automatic: fires once per trigger pull.
Burst: fires a set amount of rounds (usually three) per trigger pull.
Ballistic weapons: fires any sort of projectile, usually bullets but also refers to energy weapons or explosives.
Flamethrower style weapons: Fires a spray of either fire or energy. While the game still counts ammunition in the same units as ballistic weapons, it's more like you fire a few "units" of fire per one unit of ammunition. This is why tap firing flame weapons is a good thing to do, by the way.
Aggro: Mostly refers to big zeds but applies to all enemies; their aggro is directed at who they are currently targeting. When you "soak/absorb" aggro, you are intentionally trying to get an enemy to target you instead of your teammates.
Kiting: Running away from zeds while doing damage when possible. Running around the map while being chased by a horde instead of hunkering down and holding one area is kiting.
Penetration: An in game weapon stat. Only applies to higher caliber ballistic weapons, refers to roughly how many zeds one bullet can pass through. Only refers to zeds, bullets cannot pass through objects, walls, or doors.

Playstyle and role: Specialize with melee weapons and a couple of projectile weapons, to block choke points with your body and take aggro from large zeds so your teammates can help kill them. Basically, you're the team tank. Your growing damage resistance and immunity to clot grabs encourages you to spend most of your time in zeds' faces, but you have to be aware of high damage close range attacks on Suicidal and up, particularly Sirens in groups, and Husk flamethrower/suicide. Melee combat in Killing Floor is actually very fluid, but takes getting used to. Attacks are directional, and you have to "aim" where you intend to hit zeds.

Skills:
Dreadnought Vs. Skirmisher
Huge health pool vs. regeneration and speed.
If you have a decent level medic on the team, go dreadnought. You'll likely be getting buffs from the medic while also giving them XP, money, and their own buffs. If you don't have a reliable source of healing, skirmisher lets you be self sufficient. You have to know when to run away and recover.

Vampire Vs. Butcher.
Health regen on kill vs. Attack speed and damage.
I personally would never use vampire. It seems to have been designed with dreadnought in mind, but playing without a medic. It will make you more tanky, but the attack buffs from butcher are substantial and you'd be plenty tanky already. I will solidly vote for butcher all the time, but vampire plus dreadnought may allow you to hold a doorway without a medic. The heal rate is capped, which is the main problem with the vampire skill.

Resistence Vs. Parry
Flat Siren and Bloat damage resistence Vs. massive buffs after a successful parry.
Again, I vote parry all the time. Parrying is a cornerstone skill of playing berserker, and the buffs you gain on a successful parry are huge. Also consider that the damage resistence from parry is greater than that from resistence, and applies to ALL damage types. Even if your timing isn't great, you can run up to a few trash zeds, parry basically any time, and you'll likely block one of the attacks and get it. Parry is flatout better unless you really, truly struggle to time your blocks.

Power Vs. Massacre
Boost heavy attacks vs. boost light attacks and small attack speed increase.
Depends on the team comp honestly. If you have dedicated big zed killers and all you're doing is holding a choke point, light attacks will get the job done just fine. If you're primarily doing the damage to big zeds, especially with the Pulverizer, Power is going to help you out more.

Berserker Rage Vs. Spartan
Heal in Zed time and zeds run away vs. SANIC SPEED
You ever notice how literally every 25 berserker ever goes superfastmode in Zed time? It's just... use Spartan. It's fun. It's good. It's not even a choice.

Weapons:

Crovel: Starting weapon. Does slashing damage, very good trash clearer. Only marginally worse than the Katana, perfectly fine to run this until you can afford a top tier weapon. Sideways attacks are good for cutting off heads. Forward power attacks good against bloats and rioters.

Katana: Small upgrade to the crovel. Swings a bit faster, most charatcers have some nice voice lines, but only a marginal improvement. Best used as an improvement over the crovel after you have your more expensive weapons.

Nail Gun: Kind of a weird one. It's one of the only ranged weapons you have access to, capable of firing one nail or multiple in a shotgun style. Most skills apply to melee weapons only, so it's not going to be useful most of the time. Has a very niche use as a lower level berserker for killing zeds you can't safely facetank yet, like Sirens and Husks. Generally useless, though.

Zweihander: I think you get this as a promotional item if you own Chivalry: Medieval Warfare. If either you or someone else in the server owns the game, anyone can buy it. Think of it as an upgrade to the katana. Lots of slashing damage, good for clearing trash not not so much big zeds. Good for variety, not super meta.

Pulverizer: Very good tool for big zeds if you have to deal most of the damage. Deals crushing damage on light hits, which is good against scrakes, and explosive damage on heavy hits, good against fleshpounds. Can kill weak trash pretty easily, tends to stun and knock down slightly larger zeds. The heavy explosive hits are good against almost anything, especially with the Power skill, damage fleshpounds, one shot sirens or husks, all around great weapon. Requires reloading.

Eviscerator: Very versatile top-tier weapon. Both ranged and melee weapon. Primary fire launches a saw blade with the help of a laser sight that does RIDICULOUS damage, alt fire uses a gas powered buzzsaw to deal slashing damage in front of you. Use the ranged sawblades against bosses or big zeds. A couple of sawblades to the head should kill scrakes or fleshpounds on any difficulty, and bosses will just melt if you keep nailing the head. The secondary buzzsaw is just kind of a bonus, not the main use. Fired saw blades are recoverable. You can parry with this weapon.

Bone Crusher: Good main weapon if you're full on facetanking or choke holding. Shield provides a lot of protection, club does crushing damage, good against scrakes. You're sacrificing some personal damage output in favor of survivability, use when you have teammates to kill big zeds. Good for tanking bosses too.

Static Strikers: Personally haven't used them much. The shock effects from heavy attacks are capable of stunning zeds and preventing abilities, making them useful against zeds that are normally dangerous to face tank. Not ideal for fighting big zeds, but certainly possible. Recommend using these alongside a pulverizer or bone crusher maybe.

EMP Grenades: Deal very little damage, stuns zeds in an area. Affected zeds will have a visual electric effect while they're affected. Smaller zeds will be stunned completely and walk around aimlessly for a few seconds. Larger zeds will still target players but can't use abilities. They can do basic melee attacks but Sirens won't scream, Bloats won't vomit, and most importantly big zeds won't rage. Best used right before you run up into something dangerous, and when you intend to kill it almost immediately.

Other tips:
- If a hold fails and the squad needs to run, you're the best person to lead the way.
- If a teammate is getting swarmed, melee weapons are usually the best means of killing or stumbling those zeds quickly.
- With your ability to stun and soak aggro, you're the best equipped to start fighting a big zed. Be considerate of the current situation, and take a quick look around if possible. If your squad is currently occupied, ask for help with your mic or voice commands.
- Armor isn't useless, but is less important for you than other perks. You can forgo it in earlier waves to save money.

Playstyle and role: The commando is a trash killer, but with the flexibility to help out the team in several ways. Focus with assault rifles to kill trash with some amount of precision, and help out in killing big zeds when possible. You're usually best off a little further back from the action, picking off trash and medium size zeds. You passively help your squad by highlighting stalkers (and the patriach), from almost anywhere at higher levels. You also provide the unique benefit of extending zed time. The more level 25 players are on your team, the more exponentially powerful this becomes, but it's useful for anyone. You can also see enemy health. On your own, you can make personal judgement in helping with big zeds, or use your microphone to call out targets. Just keep in mind only you can see these health bars.

Skills:

Tactical Reload Vs. High Capacity Mags

Fast reloads (20%) vs. larger magazine capacity (50%).
Not terribly consequential, honestly. In lower levels tactical reload is probably more useful, as it provides a 20% faster speed. In higher levels you get a passive reload speed increase, and assault rifles don't usually take long to reload anyway, so the increased mag size may be helpful then. High capacity mags is most useful for the AR-15 and SCAR-H, with magazine capacities of 20 each upped to 30. High capacity mags on other rifles is usually a bit overkill. Two very simple skills that are both useful.

Fallback Vs. Impact Rounds

Increase weapon swap speed and pistol/knife damage vs. dramatically increased stumble power. The main appeal of fallback is the swap speed, though the pistol buff is useful in earlier waves. In earlier waves, you will also be killing almost everything with one headshot, so the stumble power won't be terribly useful. On later waves when dealing with large amounts of medium size zeds, stumble power is great for buying yourself and squadmates time. Also useful against big zeds, but don't forget that clearing trash is a higher priority for you. If you have a SWAT on your team, SMGs naturally have a higher stumble chance rendering impact rounds a bit redundant. Later waves and no SWAT? Run impact rounds. Early waves and trying to save money? Run fallback. Note that Fallback only applies the damage bonus to your 9MM, and dual 9MMs. Other pistols will not get the bonus.

Tenacious Vs. Prepared
Small health and armor increase vs. higher ammo capacity.
Both straightforward and useful at any time. Tenacious tends to be more useful for small squad and solo play, whereas prepared is more useful for longer, larger late game waves. Also useful if you run weapons in full auto more than single fire. Choose based on your weapon choice and game size.

Hollow Point Rounds Vs. Eat Lead
Damage bonus and recoil reduction vs. Huge mag size increase
I would take Hollow Point Rounds over Eat Lead at any time. The recoil reduction is nice but the damage bonus is enough to make several mid size and trash zeds take one less bullet to kill, or kill outright with a headshot instead of just a decapitation. Doubling magazine size is just overkill, and not a good choice over the alternative. Suppressing fire is generally not terribly useful against zeds. The only real niche use I can see for this is using it with the Stoner LMG to basically infinite stumble a few big zeds, but you'll run out of ammo real quick doing that. Stack with high capacity mags for ♥♥♥♥♥ and giggles, but otherwise not very useful.

Tactician Vs. Machine gunner
Real time reload and swap speed vs. triple fire rate and small damage increase
I'd lean toward machine gunner in general, but tactician has niche uses. If you're running an M16, you can toss out a couple of grenades in that time and swap back to your main weapon. Would NOT recommend against big zeds but could be useful against a few Sirens or Husks. Still, Machine gunner could let you just as easily mow them down in that time. Very useful against scrakes.

Weapons:

AR-15: Starting weapon. Quick tip, use alt fire to swap off of burst and use it in single fire. It's basically a slightly stronger 9MM (It literally is firing 9MM rounds, fun fact). 20 rounds in the early waves is honestly not bad. Great for maintaining zed time. Hopefully you're comfortable hip firing because it only comes with the ironsight, which isn't great. Ammo is dirt cheap if you want to run it as a secondary weapon (i.e. with a Stoner LMG and med pistol).

SA80 L85A2: Despite using a 5.56mm bullet, the damage per shot is actually the same as the AR-15. However, it does have a few advantages: holographic sight, full-auto capable, larger magazine size of 30. If you're running a lower difficulty or smaller squad game, it's generally not worth the money and you can sell/rebuy the AR-15 for ammo. Higher difficulties and larger games though, it's a useful stepping stone.

AK-12: Good all-round weapon. Decent fire rate, bit more damage per shot, only does full-auto or 3 round burst. Past the first couple of perk levels, will kill crawlers in one hit anywhere and gorefasts with one headshot. Comes with a red dot sight and 30 round mag. You want to shoot fully automatic with a bit more punch, this is the gun for you.

SCAR-H: It's actually a DMR pretending to be an assault rifle. Fires a big 7.62 bullet, but has a smaller magazine size of 20. Comes with full-auto and single fire capabilities. It's a headshot machine, killing almost any medium or smaller zed with 1-2 headshots. Also better in single fire because of the recoil, but full-auto is fine for "oh ♥♥♥♥" moments where a scrake starts running at you or you need to run and clear a path. Best run with a full-auto capable rifle for backup, but very reliable at what it does. Great for helping with scrakes, but don't overdo it.

Stoner 63A LMG: Roughly the same recoil and damage as the AK-12, but it's a belt fed LMG. Comes with a base capacity of 75 and ridiculous fire rate. It's not super meta, but very fun and perfectly usable. Comes with only the ironsight and full-auto fire mode. Good to hipfire with, and very good when running and clearing a path. Consumes ammo real quick though, that's it's limiting factor as a main weapon. Recommend running with an M16 or SCAR-H. Trigger discipline is your friend.

HMTech-401: Medic assault rifle. As one of the medic's top tier weapons, it's actually a very good gun. Comes with a magazine size of 40 and only fires in full-auto. Even with no skills aiding the healing darts, it heals quite a bit and recharges fast. If you want to play commando and don't have a medic, use this gun. Just understand, you're still definitely not a medic, but you can get a LOT done with this rifle. Recommend running with something else for a bit more power when you need it.

M16 M203: Assault rifle with underbarrel grenade launcher. Not the strongest assault rifle but the ability to shoot grenades is super useful. You're not going to have the area clearing power of a demolitionist but this thing will delete sirens or rioters (with a headshot) real quick, or clear 5-10 zeds real close together, and you can help with fleshpounds, but REALLY don't overdo it. Depending on the difficulty you do 40-10% of a fleshpound's health per grenade. Remember the recent change, if you interrupt the grenade's reload you need to alt fire to manually reload. The rifle itself is roughly on-par with the AK-12 strength wise, only comes with an ironsight. One of my personal favorites, super useful to run alongside your main weapon.

HE Grenade: As simple as can be. Just explodes and does explosive damage in the area. Good for clearing a small patch of trash zeds, can throw several at a fleshpound in an emergency, good to throw at a door that's been welded right before it breaks.

Other tips:
-As versatile as the commando is, remember trash clearing is your primary job. In more difficult multiplayer games, your medic rifle or M16 just won't cut it.

Playstyle and role: Specialize with shotguns to throw large amounts of damage down choke points. Weld more proficiently than other perks and players can interact with you to get ammo mid wave. Shotguns have the particular quirk of firing projectiles. Pellets have travel time, and you will need to lead targets that are farther away. While the damage output of shotguns can be ridiculous, you are in fact usually best supplementing damage dealt by another perk. You can take big zeds head-on with your AA-12 or Doomstick, but on higher difficulties your margin for error is pretty damn small. Welding doors is something you have to be really careful of in higher difficulties; you can get your whole squad killed with one bad weld. If in doubt, don't weld it.

Skills:
High Capacity Magazines Vs. Tactical Reload
50% larger magazine size vs. 20% faster reloads.
This depends on what weapons you intend to be using. Shotguns that reload one by one are best used with tactical reload, whereas magazine fed shotguns do have long reloads but benefit greatly from the huge magazine size boost. The AA12 in particular will have a massive 30 round drum, and that is a LOT of damage potential. With your team, you can obliterate multiple scrakes without reloading. However, the benefit with smaller magazine sizes is pretty meager; the double barrel boomstick doesn't get an increase at all. Choose depending on your loadout; smaller squad games also won't call for such long periods of sustained fire, and the reload speed increase will be more useful there.

Fortitude Vs. Salvo
50 more health Vs. 30% damage increase
Since the Support isn't a class generally intended to be tanking damage, and instead dishing it out, I personally don't see the appeal of the health bonus unless you're closely working with a medic who is constantly buffing you while you facetank big zeds. If you are not working that closely with a medic, take the damage bonus. Hell even if you are, but you have a berserker, I still say take the damage bonus.

Armor Piercing Shot Vs. Tight Choke
Increase penetration vs. Tighten Spread
While not everyone will necessarily like how a choked shotgun feels, the increase to penetration becomes increasingly redundant. By level 15 when you unlock these skills, you already can penetrate 2-3 zeds with most shotguns. Tight choke will turn most shotguns nearly into rifles. You will be better served aiming for the head than center mass, but there is much greater damage potential in doing so. More useful for the AA-12 and M4 combat shotgun, can be a bit uncomfortable for the starting SG500. The double barrel boomstick and doomstick don't seem to change at all with the tight choke skill.

Resupply Pack Vs. Concussion Rounds
Give players more ammo and armor, and more carried ammo vs. Increase stumble power.
Resupply pack is going to be the go-to almost all the time. You will give your squadmates 30% of their ammo per wave, regardless of what tier weapon they're using, and free armor on top of that. You even get a personal bonus of carrying more ammunition for yourself. Stumble power by comparison isn't nearly as useful of a skill. You'll kill almost all trash zeds in one shot, and your top tier weapons already have a pretty high stumble chance as well as ridiculous damage against bigger zeds, especially scrakes. Even in solo play or small games, I'd take resupply pack any day.

Penetrator Vs. Barrage
Infinite penetration vs. Real time fire rate
Both very situational to use, but the situation where barrage is useful is far more common. A full drum from an AA12 to the head will kill any big zed at any difficulty. If you happen to be looking at one and zed time comes up, you can put 3/4 of that mag into their face before zed time ends. The only time penetrator would be useful is if you're looking at a long corridor and have one shot to fire. At level 25, you already have a huge amount of passive penetration making the skill completely redundant. Barrage any day.

Weapons:
SG 500: Starting weapon, pump action shotgun. Honestly not great. Benefits from your passive penetration and damage bonuses but long time in between shots, and reloads one by one. Comes with a base magazine size of 8. Even in the starting wave you have to manage your ammo carefully, and try to line up multiple zeds to shoot. Would recommend swapping ASAP.

HZ-12 Multi-action: Double barrel pump action shotgun. Very flexible, and a good secondary shotgun later on. Benefits from any perk skills, and is magazine fed. Has a magazine size of 16, extendable to 24 which is a great amount of sustained fire. Needs to be pumped every two rounds fired, but those two rounds can be fired as quick as you pull the trigger. Can kill most medium size zeds with two shots, not viable against bigger zeds.

Double barrel boomstick: Classic sawed-off double barrel shotgun. Magazine size of two and cannot be extended. Has a very large spread, and cannot be tightened (or if it can, it's hard to notice and doesn't really change much). Constantly in a cycle of dealing damage and reloading. Damage potential is great but it actually can't hold much ammo, and you have to get really close to bloats and husks to kill them. Fun to use, I think the HZ-12 is more reliable. You get 6 shells per ammo box, and can use alt fire to shoot both barrels, with a very high stumble chance.

M4 Combat shotgun: Semi-automatic shotgun. Comes with a red dot sight, a bit more precise than other shotguns, even without a choke. Capable of good sustained damage, but reloads one by one, and can't deal enough sustained damage to compare to the AA12 for killing big zeds. Nice for variety, but not great.

AA12: Fully automatic shotgun. Comes standard with a massive 20 round drum, extendable to 30. This is one of your main choices for dealing huge sustained damage to big zeds, especially scrakes. Ammo is expensive and consumed quickly, so it's best to have another shotgun for killing trash, but in a pinch you can clear a path with ease. Only comes with an ironsight. Can be swapped to semi-automatic if you prefer.

Doomstick: As designed, the double barrel boomstick, but more of everything about it. More damage, more stumble power, a lot more weight and a lot more expensive. This is your other option for killing big zeds. You basically want to get as close as possible to their head and use the alt fire to fire all four barrels at once. I personally don't use this very much at all, but it's a viable alternative. You're going to want to run something more reliable for trash clearing. Like the double barrel, the magazine size cannot be extended (the trader will say it holds six rounds) and the spread cannot be noticeably reduced.

VLAD-1000 Nailgun: Cross perk weapon because it's got a shotgun fire mode. Pellet count is small, damage is poor, doesn't even really have a niche use for a support. Pretty terrible all around.

HMTech-301 Shotgun: Medic shotgun, semi automatic and magazine fed. Actually a usable weapon, a bit like a slightly weaker M4. At higher levels with an increased weight capacity, not a bad idea to run one to help out your medic, but I wouldn't use it as a main weapon. Small pellet count, damage is ok but not great. Without a choke, the spread can be annoyingly random.

Incendiary Trench Gun: As much as I want to love any M1897, it's not a good cross-perk weapon. The direct damage from the pellets is tiny. The off-perk afterburn is negligible. The magazine size is 6 and it's loaded one by one. It's pump action. It doesn't really benefit from any of the Support's skills or passive bonuses, no real point in using it.

Frag grenade: Similar to the High Explosive. The explosion itself is much smaller, but it sends pieces of shrapnel in all directions which does most of the damage. Smaller initial blast, but a slightly larger effective range. Most useful against large groups of trash.

Other tips:
Stand a little farther back from the trader between waves.

Playstyle and role: The most important job of the medic is obvious, use your medic weapons' alt fire to heal teammates. That being said, you'll want to get familiar with less obvious mechanics. All medic weapons (minus the grenade rifle) fire darts with the alt fire. These darts come from a recharging "energy" system, all medic weapons have 100 charge but lower tier weapons consume more charge per dart, and recharge slower. All weapons except the Hemogoblin heal the same per dart. If you aim at an injured teammate, down sights or not, the dart will lock on to them after about half a second. The gun will make a noise, and the sight will have an additional green crosshair over it to signify the lock on. Darts that are locked on will change direction mid flight and not miss, but they can hit other zeds, players, or obstacles in the way. Four of the available skills to the medic are various buffs delivered through healing other players. Any healing you do to yourself, through your syringe, grenades, or skills, will apply those buffs to you. You also become pretty tanky at higher levels, so you don't need to fear for your life as much as some players seem to (but don't be a battle medic in multiplayer. Nobody likes a battle medic.) When not healing players, you should be helping clear trash.

Skills:
Symbiotic Health Vs. Resilience
Self heal when healing others, and health increase vs. increasing damage resistance with damage
This is one of the most one sided choices there are. Symbiotic health not only heals you when you heal others (which should be constantly), but any buffs you apply with later skills apply to you as well, and stack. These buffs include speed, damage, and damage resistance. Resilience, on the other hand, takes away your ability to passively self heal in exchange for up to 50% damage reduction when you're at half health or less. It's just... no, I can't think of a single situation to use resilience in. Symbiotic health, 100% of the time.

Adrenaline Shot Vs. Combatant Doctor
Speed boost on heal vs. movement speed increase and big magazine size boost
Rule of thumb is in multiplayer, especially on higher difficulties, I would always recommend the buff skills. Adrenaline shot is always useful. When healing, you can help a teammate get away from danger and avoid hits in the process, and speed yourself up to reposition afterward. You can also speed boost full health players, though you can't lock on, useful for people who died and want to get their weapon back. The benefit of having a big magazine size is negligible when most medic weapons don't do much damage, but makes sense for solo play. Also, you passively gain movement speed with level.

Focus Injection Vs. Acidic Rounds
Damage boost on heal vs. Bullets deal damage over time
Buff skill, go-to for multiplayer. That being said, the damage over time is only useful against the weakest of trash. Your shots will always trigger the poison, but it's on a delay of about half a second, in which time you may as well shoot them again or let them die because you decapitated them already. Could be marginally better in solo play, but in general isn't a very well executed skill. Has very niche uses like interrupting a gorefiend block early, but not reliable enough at it to do so effectively.

Coagulant Booster Vs. Battle Surgeon
Damage resistance on heal vs. 20% damage increase with weapons
The non buff skill is more useful in this case, but still not by enough. Damage resistance is really helpful for perks that facetank damage a lot, and for getting people out of danger of course. The damage boost is most noticeable with the shotgun and assault rifle, good for solo play.

Airborne Agent Vs. Zedative
Become a healing grenade in zed time vs. deal damage over time and slow zeds
I run airborne agent almost exclusively and most other 25 medics I see do so as well. You literally become a healing grenade, at no cost whatsoever. You can run near people close to you to heal and buff them, and it's also pretty deadly against the weakest zeds. The damage over time with zedative is, again, piss poor though the slow can be useful. However, in using airborne agent, you are completely justified and indeed encouraged to let everyone know "My farts smell like Frebreeze."

Weapons:
HMTech-101 pistol: Starter weapon, magazine fed pistol. Honestly might be a little weaker than the 9MM, has the same capacity of 15 rounds. Darts recharge slowly and consumes 50 charge per dart. Almost useless as a weapon.

HMTech-201 SMG: Fully automatic SMG. I think (could be wrong) it has the lowest per-shot damage in the game. Has a magazine size of 40 and is capable of killing a few weak zeds but not much more. Not much better than the pistol as a weapon, but has a nice firing sound that people seem to find amusing. Consumes 40 charge per dart, and heals only slightly more than the pistol. I personally skip this and run the pistol for an extra wave or two, but if you're feeling unprotected, go ahead and get it.

HMTech-301 Shotgun: Semi automatic Shotgun. Holds 10 rounds, but can be a bit inconsistent. The pellet count is a bit low and the spread a bit high, so sometimes shots that should be good end up not doing much damage at all. A good secondary weapon, but not really great to run as a primary. Consumes 35 charge per dart and charges noticeably faster than the SMG. Good backup source of healing darts at lower levels if you use up all the darts of a higher tier weapon. Also very capable of hitting scrakes hard, but don't do that unless you're the last one alive or it's the end of the wave.

HMTech-401 Assault Rifle: The real meat and potatoes of the medic's arsenal. 40 round magazine, fully automatic, decent damage per shot but has a bit of recoil to it. Consumes 30 energy per dart, and recharges real quick. At higher levels, you can heal basically infinitely. The staple main weapon of me and most other medics, good to run with almost any other medic weapon you like. Can reliably kill up to medium zeds with ease, kills the trash with a headshot or two.

Hemogoblin: Shoots syringes that debuff zeds. Also has a slightly higher base heal per dart than other weapons, and recharges about as quickly as the shotgun. No real point in debuffing anything less than big zeds, and big zeds need to be shot 2-3 times for the maximum effect. Debuffed zeds move more slowly, deal less damage, and take more damage. They'll be clearly visible with pale skin, shrunken limbs, and an icon over their head. Best run with an assault rifle as a more reliable means of damage.

HMTech-501 Grenade Rifle: Similar to the 401 as a rifle, slightly smaller magazine size of 30 and more damage per shot. Shoots healing grenades instead of darts, and these consume ammunition. Useful if your squad is staying still in a confined space, but not much else.

Healing grenade: After a short fuse time, disperses healing gas in a small area. Players inside the gas will be healed (about five health per half second, you won't heal upon leaving the area. Keep this in mind when you're on the run.) and zeds will take poison damage. Useful against weaker zeds. This gas goes through welded doors. Bug or feature? Yes.

Other tips:
-Healing priority is not set in stone, but try to focus on people in more immediate danger, and have the mindset of saving lives instead of healing damage.
-You can use grenades to buff yourself when at full health.
-Your life is the most valuable. People will do dumb things, don't kill yourself for a lost cause.

Role and playstyle: Use explosive weapons to clear large groups of trash and annihilate large zeds, especially fleshpounds. Your damage output per shot is incredible, but offset by most weapons requiring a minimum arming distance, as well as self damage. Demolitionist is very much a team-oriented perk, your weapons don't really let you fend for yourself much. You also have to be aware that on higher difficulties you can't kill things in one shot and pissing off big zeds when the team isn't ready is a big no-no. You have "reactive armor" which means that once per wave, a hit that would kill you instead causes a large explosion, leaving you with five health. This won't stop damage over time, be aware. Teammates can get a free grenade from you once per wave. You can also set door traps by welding doors. The weld will become orange and upon breaking, the door will explode with enough damage to kill trash and most mid size zeds. You can't trap a fully welded door, just unweld and reweld to set it.

Skills:
Bombardier Vs. Shock Trooper
Increase damage vs. Reload 20% faster
Both are good, it depends on the game size. For larger games and higher difficulties, I recommend shock trooper since you won't generally be killing things in one hit. If it's going to take two rockets to kill a fleshpound, may as well fire the second one 20% faster. Lower player count and enemy health, go for the one shot.

High Impact Rounds Vs. Extra Rounds
Increase direct hit damage Vs. Extra five rounds per weapon
Depends on your weapons and how far into the game you are. Early game, when the M79 is your main weapon, run extra rounds. You can kill most mid size zeds with one headshot, and doing so is an important skill to have playing demolitionist. As soon as you get an RPG though, swap over to high impact rounds to maximize your effectiveness at your job: use your top tier weapon of choice to kill big zeds as quickly as possible.

Sonic Resistant Rounds Vs. Fragmentation Rounds
Bypass siren screams vs. much larger area of effect
Both of these seem good but they have caveats. Bypassing siren screams is convenient, but good timing can also get the job done, making the greater area of effect seem more tempting. While the area increase is large, the lethal range will be about the same. You'll just be stumbling and knocking down zeds more often, which may be annoying to more precise perks on your team trying to clear trash. Honestly, neither one of these is spectacular, I prefer being able to delete sirens without having to wait, but if you're playing in an open map, fragmentation rounds will probably be more useful.

Armor Piercing Rounds Vs. Concussive Rounds
Substantially increase headshot damage vs. substantially increase crowd control effects
Both of these are actually really good, but for different reasons. The increase to headshot damage is useful for specific weapon and zed matchups, particularly M79 against rioter, and RPG against scrake. Even with high player counts you can one shot important zeds if you can be patient and land those headshots. However, being realistic, you won't have time to line up some shots and concussive rounds becomes much more useful. If a fleshpound is already enraged the ability to crowd control it, even for a little while, is super useful. Smaller squad and less chaos, armor piercing rounds. Large squad and a lot going on, concussive rounds.

Destroyer of Worlds Vs. Mad Bomber
Huge explosion and cloud of damage over time vs. real time shooting and reloading, plus area
Most 25 demolitionists run destroyer of worlds. First of all, ♥♥♥♥♥♥♥♥ is the nuke effect satisfying, but the cloud actually does a LOT of poison damage real quick. Most zeds that walk through will be crowd controlled, walking around aimlessly for a couple of seconds if not dying outright. It's very useful for cutting a choke point off. Mad bomber is more useful for the M32 specifically, but it's more a niche use if you really like the weapon. Even that can fire two rounds, both nukes, in zed time with destroyer of worlds.

Weapons:
HX25: Starting weapon, grenade pistol. It's one of the, if not the worst starting weapon. It functions kind of like a shotgun, firing a few explosive pellets. It can kill up to a gorefast if all the pellets connect on one target. It can kill mutiple clots if they're standing right next to each other. It requires a reload after every shot, can't headshot, and is generally useless. On the bright side, no self damage and it's worth slightly more when you sell it. Recommend getting rid of it ASAP.

M79: Single shot grenade launcher. Actually seems a little underwhelming damage wise, but can kill important zeds with a headshot. Can kill bloats and rioters with one headshot past the first few levels (just aim with the ironsight, you usually won't be far enough away to need to compensate). You can get it second wave and ammo is actually pretty cheap. Can clear decent size groups of trash, you'll learn to aim for the strongest zed in a group for maximum effectiveness. Has a minimum arming distance, but if you need to kill something right in front of you, you can shoot the grenade into their face, or jump and shoot the ground nearby. The latter will damage you slightly, a negligible amount in higher levels. Do NOT use this to try to kill fleshpounds.

C4 Explosives: Thrown, triggered explosives. It's for a playstyle I never use, and never see others use for that matter, but I'm pretty sure it's viable. The reason I think C4 goes neglected is because door traps make it seem unnecessary, but a higher base damage and ability to set multiple charges makes it stronger in theory. Go ahead and try it, but not without an actual weapon first.

RPG-7: Single shot rocket launcher. Rocket has a minimum arming distance, a bit further than the M79. One of the highest damage per shot weapons in the game, one of the best tools for killing fleshpounds. You're going to be limited by the ammo capacity, so you can't realistically use it to kill groups of trash and big zeds at the same time. The travel time of the rocket is actually pretty short at mid range, not a problem once you get a feel for it. It will generally take 2-4 rockets depending on player count and difficulty to kill a fleshpound, so be aware of the ammo and time it will take. The area of effect also isn't much bigger than the M79, so always aim for direct hits. Try to make the first hit a headshot, even without skills boosting headshot damage it might mean one less rocket to kill your target.

M16 M203: Automatic assault rifle with underbarrel grenade launcher. Designed to be a lifeline to a demolitionist without protection, the rifle itself isn't very good in your hands. Your skills only apply to the grenades, which do about the same amount of damage as the M79's but with a smaller area of effect. You can keep small amounts of trash off of yourself if you aren't getting protection, but you're still going to get overwhelmed if you push your luck. It's still a good secondary weapon, personal preference between the M79 and M16.

Pulverizer: Considered a cross perk weapon because it technically deals explosive damage. Demolitionists do NOT want to be in zeds' faces. Wouldn't recommend.

Seeker Six: Multi-shot rocket launcher. Fire mode changes between guided and unguided rockets, and it has a capacity of six rockets. These rockets are smaller than the RPG's, but with roughly the same travel time. They do a little more damage than a 40MM grenade, but with a much smaller area of effect. Usable, but underwhelming. Not a big zed killer either.

M32: Semi-automatic grenade launcher. Same grenades as the M79, but holds six and has a holo sight. Fun and good for variety, but RPG is better.

Dynamite: High damage, long fuse time. Will explode on contact if thrown directly at a zed. Good for clearing your immediate area in an emergency, mind the self damage.

Playstyle and role: Trash clearing and area denial is the name of the game. You specialize with flamethrower type weapons, but have access to a handful of more traditional ballistic weapons with incendiary ammo. The ballistic weapons are generally weaker than those of other perks, and flamethrower weapons lack outright killing power. Rather, you deal a lot of damage over short periods of time, covering small choke points in ground fire that kills trash almost on contact, and otherwise crowd controlling zeds by causing them to panic when burning. You, however, MUST be mindful of what you're damaging, especially on higher difficulties. Making larger zeds panic just makes them hard to hit for the rest of your squad, and leftover ground fire can cause you to accidentally enrage big zeds that your squad isn't ready for. The lack of direct killing power makes firebug a more team oriented perk, and a good one can be a great asset, but poor role performance can be a MASSIVE hindrance.

Skills:

Bring the Heat Vs. High Capacity Fuel Tank

Large damage increase vs. double ammo capacity
Depends on what weapons you plan to use the most. If you plan to be using traditional flamethrower style weapons, high capacity fuel tank may prove more useful, especially with the starting caulk n' burn. However, the flamethrower and microwave gun both have a capacity of 100, and 200 is a little overkill as their reloads aren't horribly long. However, using flamethrower weapons most of your damage will come from ground fire, which is unaffected by bring the heat. Overall High capacity fuel tank is going to be more useful for the caulk n' burn with ground fire, bring the heat will be better for everything else.

Barbecue Vs. Ground Fire
Longer burning effect vs. create slowing and damaging ground fire
No contest, ground fire 100% of the time unless you're only using ballistic weapons for the memes. Ground fire is a separate entity from your flamethrower weapon; ground fire from any weapon is the same. It creates a noticeable blue flame after spraying the ground for about half a second, and it greatly slows and damages zeds passing through. You can cause ground fires by spraying fire at zeds' feet, doing damage from both the weapon and ground fire. You can slow big zeds after they're raged, and effectively kill trash that walks over ground fire. Compare to a longer (not stronger) burning effect. This means if you hit a clot with one bullet, now in a couple of seconds they'll burn to death. Never worth it in multiplayer, always go ground fire.

Napalm Vs. ZED Shrapnel
Burning effect spreads between zeds vs. zeds randomly explode and stun others
I'd lean towards zed shrapnel the majority of the time. Whereas the effect of napalm will constantly cause many zeds to panic and run around randomly, making it harder for your squad to help, stunned zeds will stand still and be considerably easier to hit. As a trash clearer, you'll be setting off these explosions a lot and it's going to help everyone out a lot more.

Heat Wave Vs. Firestorm
100% stumble chance vs. Increase range of flamethrowers
Again, no contest, heat wave. This stumble power is one of the most useful tools the firebug has. Any zed, this includes enraged big zeds and bosses, will stumble if you spray them point blank. There's a limit on how often this happens of course, but it's still super useful. You can almost do the job of a berserker taking aggro with heat wave (but you don't have the damage resist or parrying ability, don't overdo it). If your team has engaged a big zed, buy them more time by running up and stumbling it. Interrupt dangerous close range attacks by stunning the zed, it's just always useful. The ranged increase is pretty negligible past the caulk n' burn, and doesn't have any effect on ballistic weapons.

Pyromaniac Vs. Inferno
Shoot in real time with infinite ammo vs. slow and more damage over time
Pyromaniac, no contest. Particularly effective with ballistic weapons, but useful for flamethrowers too. Create a whole bunch of ground fire, or headshot lots of things with spitfires, it's useful for any loadout. Compare to slowing zeds while time is already slowed, and increasing damage over time... while time is slowed. Run Pyromaniac all the time.

Weapons:
Caulk N' Burn: Starting weapon, flamethrower. Has the smallest capacity and direct flame damage, but has other perks. Unlike the flamethrower, the fire will never hurt you. It's dirt cheap to run, it's cheaper to sell and rebuy it than purchasing ammo. Also ground fire is a separate entity from the weapon, so the caulk n' burn is capable of dealing the same amount of ground fire damage as any other weapon. It's actually perfectly fine to run for the first few waves until you can get a microwave gun, or also useful to run with a top tier ballistic weapon. Good trash clearing weapon at any point in a game.

Spitfire(s): Flare gun/incendiary pistol. Shoots fiery projectiles a bit larger than bullets, can be dual wielded. A solid ballistic weapon, especially for players with gunslinger experience. Does respectable damage with headshots, and can kill weaker trash in one hit to the head. A favorite of 25 firebugs to shoot ridiculously fast in zed time. Very light, good to run with a microwave gun.

Dragonsbreath: Incendiary pump action shotgun. I want to love this weapon, but it's just not very useful. The direct damage of the pellets is pathetic, and the damage over time skills are greatly outshone by their counterparts. It's pretty, but nearly useless.

Mac 10: Incendiary SMG. Very good ballistic weapon. Does low damage per bullet, but still good trash clearing power, comes with a subpar ironsight though. Best used alongside a flamethrower weapon, can't really deal with anything more than mid size zeds.

Flamethrower: Traditional flamethrower. An upgrade in some ways to the caulk n' burn. Has double the fuel capacity and more direct damage. Also heavier and more expensive to run, and the fire will hurt you at point blank unless you're level 25. Not useless, but not really good enough to use over the caulk n' burn or microwave gun unless you want to use it for variety.

Microwave Gun: Top tier flamethrower style weapon. Also has a capacity of 100, causes zeds to inflate and explode. Has the highest direct damage, and still ground fire capable. All of the core skills apply to this weapon, so it's never a bad weapon to run, best used with a ballistic weapon secondary or even a caulk n' burn if you like. Has a secondary fire that shoots a projectile for multiple ammo, never particularly useful.

Husk Cannon: I have very little experience with this weapon. Nice for variety, not completely useless, but not particularly great either. Charges up and fires an explosive shot that deals additional burning damage.

Helios Rifle: Top tier ballistic weapon. Functionally like an assault rifle, capable of full auto and burst fire. Very powerful, fires fast moving energy projectiles with a little bit of travel time. A completely viable main weapon, but recommend running with a flamethrower weapon for the main role. In lower player count games, a great big zed killer.

Molotov: Glass bottle full of gasoline. Does a small amount of direct damage, mostly for applying fire damage over time to tightly grouped zeds. Not generally a very useful grenade.

Other tips:
- With flamethrowers, tap fire. You'll fire a little bit of extra flame without consuming ammo. Ammo boxes give you very little, so conservation is important.
-Inconsistent, but sometimes ground fire goes through welded doors. Never hurts to try.
-Firebug creates a lot of visual clutter. Try not to fire in front of other, precise perks like commandos or sharpshooters.

Role and playstyle: Highly mobile and capable of huge damage output. Gunslinger is the master of kiting, and dealing large amounts of precise damage while moving. The perk is at its best when working alone or taking advantage of its mobility, but when working with others is decent at trash clearing and great for killing big zeds, particularly scrakes.

Skills:
Steady Vs. Quick Draw
Reduce speed penalty and bob while aiming vs. huge weapon swap speed, recoil reduction when firing from the hip, and small movement speed increase
I think this one comes down to preference, both are good. If you prefer aiming down the sights when dual wielding, with either style, use steady. If you have a good feel for where the center of your screen is or you use a crosshair, you may prefer quick draw. Both of these skills pertain to a style of aiming, get a feel for whether you want to aim precisely or not and choose accordingly.

Rack 'Em Up Vs. Bone Breaker
Stacking damage bonus on headshots vs. Increase base and limb damage
If you can consistently land headshots, use rack 'em up all the time. The damage bonus is 10% per headshot, up to 50%. When this bonus is active, it doesn't matter where you hit zeds from that point on. 50% is a massive bonus, and can let you delete scrakes and clear trash much more effectively once you land some precise hits. That damage bonus surpasses a base boost of 20 and limb boost of 30, but if you struggle to land the headshots then it simply won't do you much good.

Line 'Em Up Vs. Speedloader
No damage penalty for shots that hit multiple zeds vs. 20% faster reloads
Depends on what weapons you plan to use. Lower tier weapons don't have the penetrating power, and won't benefit from line 'em up. It's really only useful if you plan to do most of your work with the desert eagles or .500 magnums. Even so, I find that the opportunities for lining up multiple headshots is actually pretty rare, and with weaker zeds the damage penalty for penetrating another zed usually doesn't matter. Increased reload speed is always useful, and stacks with the passive increased reload speed in zed time.

Skullcracker Vs. Knock 'Em Down
Deal stacking slow with headshots vs. higher stumble chance when shooting the chest or legs.
Again depends on your ability to consistently land headshots. The stacking slow is more useful for fighting big zeds, as it buys you more time after landing the first few headshots to decapitate and kill them. However if this is something you struggle with, stumble power is something you'll be able to use more easily, but it's not really your perk's job to crowd control regardless.

Whirlwind of Lead Vs. Fan Fire
Infinite ammo vs. shoot and reload in real time.
Neither one of these is actually all that great. Having infinite ammo during zed time is what I situationally find more useful. The lower the capacity of the weapons you use, the more useful this will be. Fan fire will allow you to mag dump into a single target, which in theory is good against big zeds. In practice, you'll pretty rarely have zed time trigger just as you're ready to fight a big zed, though when the stars do align it's useful. However, the "reload in real time" actually isn't a benefit, it'll be slower than the passive bonus you have at 25, by a pretty large margin too.

Weapons:
1858 Revolver: Starting weapon. Pair of six shooters with high recoil, low capacity, and decent damage. You can one shot trash zeds to the head with these, but you'll have to compensate for the recoil at lower levels and you'll have to be mindful of your combined mag size of 12. Would recommend getting rid of these.

M1911: Magazine fed handgun. Dual 1911s are great, reliable guns. Highest capacity of all dual gunslinger weapons, at 16 total. With the stacking damage bonus on headshot, you can kill any non big zed with four headshots or less. Pretty low recoil, easy to use. Never a bad idea to run a pair, not particularly useful to have one. Lacks stopping power to headshot rioters or fight big zeds, though.

Desert Eagle: High caliber magazine fed handgun. Dual desert eagles are great all around gunslinger weapons. They're affordable enough to use on trash and mid size zeds, but have enough damage output to fight big zeds reliably. You can also buy one early on in the game to deal with rioters, as one headshot with a damage bonus will break the helmet and decap them too at higher levels. Very versatile guns, can always recommend having a pair.

.500 Magnum: High caliber revolver. Highest damage per shot of gunslinger weapons, but lowest capacity at 5 rounds per revolver. Very high recoil. If you can manage the recoil, running two is great for destroying big zeds with a few headshots and fighting bosses. Running one is also a great backup weapon, as it holds five rounds but carries over 100 in reserve. If you end up being the last one alive, a single .500 magnum can last for a very long time. I personally always carry just one, but running two is a great set of main weapons.

AF-2011A1: Double barrel M1911 pistol. Fun and good for variety, but doesn't really outperform any other gunslinger weapons. Has the highest number capacity, but fires two shots per trigger pull, and landing both shots in the head of a big zed is a bit inconsistent. Theoretically higher DPS, inconsistent in practice. Good choice for the boss though if you don't care for the .500 magnums.

HX25: Worst starter weapon. Can't headshot. Most expensive starter weapon. Just don't.

Medic pistol: Considered cross perk because it's a pistol, but it's about the same as the 9MM as a weapon. Recommend taking one if you have the space to help your medic out.

Spitfire: Cross perk firebug weapon. The direct hit damage is ok but not great, doesn't outperform normal perk weapons but offers a little bit of fire damage over time. Use for variety.

Winchester 1894: Lever action rifle. Considered a cross perk weapon. Has a capacity of 12 and reloads one by one, actually hits decently hard. Still kinda heavy and doesn't outperform normal perk weapons, but if you like it, it's not a bad weapon to run.

SPX 464 Centerfire: Upgraded Winchester 1894. Has a red dot scope and higher damage, at slightly reduced capacity of 10. If you like the Winchester, this is a perfectly good upgrade.

Nailbomb: Small amount of explosive damage, explosion sends several nails outward that have a very high stun chance. As different zeds will be stunned in different ways, not particularly useful. Not reliably effective against big zeds.

Other tips:
-Your passive speed bonus is active no matter what kind of weapon you have out.
-Aiming with two pistols without the ironsight is good practice for learning where the center of your screen is, which can improve aim in other shooters.
-Make a habit of trying to reload in zed time. The reload speed bonus applies as long as you started your reload in zed time. By level 10 or so this bonus is very noticeable, and reloads can be done in a fraction of a second at the highest levels.

Role and playstyle: The sharpshooter is another dedicated big zed killer. Not great at dealing with trash beyond picking off specific targets like sirens, uses high damage, low fire rate weapons to deal huge amounts of burst damage. You'll have access to two archetypes of weapons, higher capacity and lower damage weapons like the Mk. 14 and Winchester that are more useful for dealing with mid size zeds, and then powerful single shot weapons like the Railgun and M99 that are best used solely for taking down big zeds with one or two shots. You will need some amount of protection from your team at higher difficulties and should try to stay back and out of harms way. The less coordinated and trigger disciplined the squad is, the harder your job is going to be.

Skills:
Sniper Vs. Marksman
Increase damage while stationary vs. Increase fire rate and movement speed
Depends on the weapon and playstyle you want to go with. There is the sniper style which focuses on maximizing damage per single shot, and the marksman style which sacrifices single shot damage output for mobility and a bit more self sufficiency. The role of the perk leans more toward a sniper playstyle, but a marksman style is viable and typically better in a chaotic game. If you want to shoot slow and hit hard, sniper. If you want to run around a bit more and focus more on mid size zeds (say you have a demolitonist already), marksman. If you run sniper, get into the habit of crouching when you stop to shoot.

Stability Vs. Ballistic Shock
Increase damage, movement speed, and reload speed while crouched vs. double stun power
Both of these synergize with the same side perk beforehand best, but can also be mixed. Stability further increases the benefits of crouching (which is reduced recoil with any weapon, any perk). The damage bonus is a substantial 30%, which is enough to kill certain mid size zeds with one headshot instead of two. The increase in stun power is more useful with a higher fire rate weapon, particularly the Mk. 14. Choose based on your loadout and previous skill choice.

Rack 'Em Up Vs. Tactical Reload
Stacking headshot bonus vs. 20% faster reloads
The stacking headshot bonus seems like it would be the obvious choice for either style, but last time I used it the skill wasn't working correctly. This may have been fixed since, in which case try using rack 'em up, especially with higher fire rate weapons. Tactical reload is only useful for either lever action rifle, which reloads one by one. Keep in mind that stability offers 20% faster reloads on its own, which makes 40% a little overkill if you're not using one of the lever action rifles. Use rack 'em up if it works, tactical reload if it doesn't or you're using the 1894/Centerfire for killing trash.

Dead Eye Vs. Always Prepared
Increase damage and reduce recoil while using sights vs. Carry 25% more ammo and grenades.
Regardless of playstyle, any shartshooter should be using their sight the majority of the time. If they aren't, they probably should be playing a different perk at the time. The minor damage bonus is good for helping cross damage thresholds, lowering the shots to kill something ideally to one. The additional ammo capacity however is good for the boss wave, or high player count games where you have a lot of stuff to kill, and find yourself running out (though if you're patient and accurate with your shots, this shouldn't happen often).

Assassin Vs. Ranger
Increase headshot damage 35% vs. 100% stun chance. Both give a 5% chance to trigger zed time on a headshot.
Truthfully, I'm not certain either of these work. In higher player count games, assassin won't always kill a big zed in one shot instead of two, and ranger won't always stun a zed which it supposedly should. However, assuming these do work, choose which fits your loadout and previous skills. Snipers should use assassin to help guarantee killing big zeds in one shot (by level 25, your less powerful weapon should already be one shotting anything else), marksmen should use ranger to stun as many targets as possible.

Weapons:
Winchester 1894: Lever action rifle, starting weapon. A surprisingly usable weapon at any point in the game. Comes only with the ironsight and reloads one by one, but by level 15 with sniper skills, can one shot sirens and anything weaker with a headshot. Can also reliably keep crawlers and stalkers off of you while hip firing. Very cheap to run, cheaper to buy and resell than it is to refill ammo. If you like it, it's completely possibly to run it with a railgun the whole game and pass the savings on to your teammates.

SPX 464 Centerfire: Same style as the Winchester rifle, but with quality of life improvements and increased base damage. Comes with a red dot scope, and reduced capacity of 10 from 12. If you like the 1894 but are lower level or are running a marksman style setup, run this.

Crossbow: The cheapest single shot weapon available. Has high damage per shot and you can reclaim missed bolts, and can also penetrate multiple zeds. Good for dealing with sirens and rioters in the early game, but not a big zed killer in the slightest.

Mk. 14 EBR: Semi-automatic DMR. The definitive marksman style weapon, has a large magazine of 20, a proper scope, and a laser sight to aid with hipfiring nearby threats. Capable of taking several shots at a single target or clearing some trash away from you in an emergency. Best used as a main weapon, too heavy to fit into most loadouts as a secondary.

Railgun: Single shot rifle, capable of lock on. My personal big zed killing tool of choice. Comes with a scope and ability to lock on for reduced damage. Though it's noted as having high penetrating power, it's a waste to use this on trash. In multiplayer games on suicidal and up, it'll typically take two headshots to kill a scrake, and three to kill a fleshpound. With the right skills and a decent level (roughly 20) you can kill scrakes with one headshot and fleshpounds with two. The weight allows you to run a good variety of weapons as a backup, either lever action rifle is a good choice. The lock on feature is generally useless because of the reduced damage (something like a 30-50% penatly) and time it takes to lock in the first place. Use alt fire to turn this off.

M99 AMR - Single shot rifle, incredibly power, heavy, and expensive. This is the definitive one-shot weapon. It is the heaviest and most powerful per shot weapon in the game, and at any level or difficulty you'll kill big zeds with one to two headshots. The weight severely limits your options of a secondary weapon, only really leaving revolvers as cross perk weapons. Your self defense ability will be more limited than usual, so your team must effectively clear trash and let you do your thing.

1858: Revolver. Sharpshooter only considers single revolvers as cross perk, so don't buy two. It's dirt cheap to buy one, and per shot it's actually got respectable damage. I think one of the rifles makes a better secondary, but the 1858 is still fine to run early game, especially alongside a crossbow.

.500 Magnum: High caliber revolver. Basically a handheld rifle in terms of damage. It's got a low capacity of 5 but it can kill almost anything with a headshot or two. It's the strongest weapon you can run alongside an M99. Expensive for a secondary weapon, but a solid upgrade from the 1858 if you like it.

Spitfire: Flare gun/incendiary revolver. Considered cross perk from firebug because it's a revolver, has somewhat low damage per shot and the ironsights are hard to use. Wouldn't recommend.

FN FAL ACOG: Semi automatic DMR. A slight upgrade from the Mk. 14 EBR. Same capacity, slightly more recoil, slightly higher damage. It does offer fully automatic fire as a close range alternative, but no laser sight. A solid choice for a marksman style setup.

Freeze grenade: (character limit) Freezes zeds for a few seconds. Big zeds may need a second or third grenade. Does a tiny amount of damage.

Role and playstyle: Specialize with low damage, high volume firepower to clear out trash efficiently. Use submachine guns to deliver sustained fire to groups of zeds and kill the weakest zeds quickly, while having the ability to kill big things when absolutely necessary. You'll also have the ability to improve your armor's capacity and protection to become incredibly tanky while you have armor. Your limitations come in the form of not having huge damage potential on hand if you find a fleshpound or two in your face, and focusing on the wrong targets will end up using your ammo surprisingly quickly.

Skills:
Heavy Armor Training Vs. Tactical Movement
Get a free 50 armor when you spawn and only siren attacks penetrate armor vs. no movement penalty for crouching or aiming down sights.
Both actually great skills for different reasons. Heavy armor training's free starting armor is nice, but the negation of all damage except siren screams is incredibly powerful. You're no berserker but you can get really aggressive in playing around your relatively short effective range, and have breathing room for mistakes. Tactical movement on the other hand allows you to crouch run while aiming. Crouching greatly reduces recoil with all weapons, so effectively this lets you run around at full speed while maintaining a great level of accuracy. Heavy armor training is most useful for normal waves, while tactical movement is great for facing the boss.

Close Combat Training Vs. Tactical Reload
Huge increase to pistol and knife damage and get free dual 9MMs vs. 20% faster reloads
For the first couple of waves, especially with lower player counts, go with close combat training and use your pistols. You'll save a good bit of money and swap over to tactical reload once you're ready to start using your main weapons. However, most weapons increase their magazine sizes to ridiculous amounts at higher levels, so the choice past the early game comes down to whether you reload or use your pistol more often. Both are viable options, start with close combat training at the game start for a little boost.

Suppression Rounds Vs. Ammo Vest
Double stumble power vs. 30% ammo reserve capacity
Suppression rounds are great for helping the team out with big zeds. Submachine guns on their own already have a high stumble chance, and increasing it further almost guarantees a stumble when you empty a mag at a scrake or non enraged fleshpound. Ammo vest is most useful for the boss wave when you're going to be emptying your mag into a single target constantly, but in high player count games you might want to run it during normal waves as well. If the squad is working together even a bit, suppression rounds. If you're really on your own or it's the boss wave, ammo vest.

Assault Armor Vs. Cripple
Gain an extra 50 starting armor on spawn (stacks with heavy armor training for 100) and increase total armor capacity to 150 vs. slow zeds up to 30%, leg shots doing so the fastest.
Being extra tanky and getting more free armor is great, and never a bad thing. Cripple is best in a couple of situations. The slow is useful in high player count games where you do little damage to fleshpounds, so you can slow it down mid charge and buy your big zed killers more time to deal with it. Also useful against the boss. Use assault armor most of the time, use cripple for the boss or specifically when your big zed killers need help.

Battering Ram Vs. Rapid Assault
Move in real time and knock down smaller zeds vs. fire in real time with infinite ammo.
Rapid assault is going to be the go-to. Free ammo and a ridiculous fire rate is useful in any situation. You can clear a whole bunch of trash real quick, or help hose down a big zed by putting 50 rounds into its face, and either one completely for free. Even if your gun is empty you can still fire with this skill active. Battering ram on the other hand, while fun and good for a laugh, doesn't really provide any practical use. There's no reason to knock a zed over when you can just kill it instead.

Weapons:
MP7: Starting weapon. Very low damage per shot SMG. One shot at lower levels will decapitate, but not kill even the weakest zeds with a headshot. For the first waves, your 9MM with close combat training may actually be a stronger weapon.

MP5RAS: 9MM SMG. Slightly higher damage per shot than the MP7, and will have a little more killing power but not much. Also only comes with the ironsight, so it's overall a pretty minor improvement. I personally skip over this one unless it's a long game and I need the stepping stone.

FN P90: High capacity SMG. Much better stopping power than the previous SMGs, comes with a red dot sight. Comes with a base magazine of 50 and can top out at 100 at level 25. Low recoil and very reliable. Kills the weakest trash with one headshot, but has a good fire rate to deal with mid size zeds as well. All around great weapon, just try burst firing to conserve ammunition.

Kriss Vector: High fire rate SMG. Highest fire rate of the available SMGs, and a tiny bit more stopping power than the P90. It'll dump the mag very quickly but offers incredible DPS. Useful for helping to shred scrakes, and devastating against trash, but limited by it's smaller magazine size and fire rate. This will go through ammo ridiculously fast, so I personally don't use it as a main weapon. Be mindful of your consumption though and this is the DPS machine.

H&K UMP45: Slower fire rate, higher damage SMG. The slightly harder hitting counterpart to the P90. It has a lower rate of fire and smaller magazine size in exchange for slightly higher damage per bullet. At lower levels, the damage may be enough to cross a damage threshold but otherwise, it's there for variety. Perfectly good and fine to use, and against the P90 it's preference. Comes with a slightly different holographic sight.

Mac 10: Incendiary machine pistol. Cross perk from the firebug, it's actually a decent weapon to use as a SWAT. The passive magazine size increase can allow it to deliver a good amount of sustained fire. The burning damage over time isn't particularly useful to a SWAT, but it has a very high fire rate that can more easily trigger other skill related abilities. A decent secondary weapon, but not incredible.

Tommy Gun: High caliber, low fire rate SMG. Comes with a drum magazine and poor ironsights. Has much higher recoil than other SMGs and a lower fire rate, for little tradeoff in a slightly higher damage. Honestly feels better hip fired than aiming, wouldn't recommend in general.

HMTech-201 SMG: Medic SMG. Cross perk from the medic. Not a great weapon, as I think it has the lowest damage per shot or is tied with the MP7. The healing ability isn't much better than the medic pistol, and the magazine size is slightly above average at a base 40. Wouldn't recommend.

Flashbangs: Does a small amount of damage with an almost guaranteed stun. The stun will not work on big zeds that are enraged, so the timing and use of your flashbangs is imporant. Use it to initiate when you have backup ready, or to shred a scrake by yourself if you really have to.

Other tips:
-As your magazine size increases, the amount you get from ammo boxes does as well.
-If you change skills between waves, you won't get free armor or pistols. It only applies when you join a game or respawn.

Role and playstyle: The resident "jack of all trades" perk, with a couple of added bonuses regardless of skill choices. The survivalist exists to bridge the gap of some perks, or partially fill multiple roles. In essence the survivalist is playing two and sometimes three perks at a time. Every perk specializes in its role better than the survivalist can fill it, but the survivalist borrows a couple of passive bonuses from other perks and has access to a couple of unique weapons, as well as a passive damage bonus to any weapon whatsoever. The Survivalist borrows heavy armor from the SWAT, taking no health damage while wearing armor and gaining bonus armor with level. You also get a global damage resistance like the berserker, and faster reloads during zed time like the gunslinger. When playing as a survivalist, you can choose to either fill roles for the team without committing to them completely, or give your team the finger and do your own thing somewhere else. Either is a valid playstyle, though I'm not encouraging the latter.

Skills:
Tactical Reload Vs. Heavy Weapons Training
Reload SWAT, Commando, and Gunslinger weapons faster vs. demolitionist, sharpshooter, and support weapons. Both give a bonus of 20% faster speed.
This simply depends on whether your aim to clear trash or kill big zeds more. Whatever the main weapon of your loadout will be, get the associated reloading skill. If you have weapons from either set, get the skill for whichever you will be reloading more. Generally speaking, heavy weapons will require more reloading. Your 9MM pistol gets the increased speed from either.

Medic Training Vs. Melee Expert
Increase healing amount and reduce cooldowns vs. increase movement speed, attack speed, and damage with melee weapons.
Both of these skills are potent enough to be useful, but I would lean towards medic training most of the time. The berserker has some unique skills that the survivalist does not, which greatly aid survivability, particularly the parry skill. If you love melee weapons go right ahead, your damage output will be fine, but you have to be very careful of what fights you pick. Medic training is always useful, either to help out your medic or be and 3/4 of a medic yourself.

Ammo Vest Vs. Weapon Harness
Carry 15% more ammo and use healing grenades vs. additional 5KG carrying capacity and molotovs
If you're using lighter weapons and/or being the team medic, go with ammo vest. With assault rifles and submachine guns, you typically won't want to be running three of them and even so, it'll likely add up to about 15KG regardless. If you're combining a couple of very powerful heavy weapons, then obviously run weapon harness. You can run some absolutely ridiculous combinations with 20KG capacity and bonuses that apply to all weapons. The molotovs are generally pretty useless.

Spontaneous Zed-splosion Vs. Make Things Go Boom
Zeds killed have a 30% chance to explode and stun nearby zeds vs. increase explosive area of effect by 40%.
Simple choice, choose zedsplosion most of the time, especially if you're focusing on trash clearing. The constant stuns will make things easier for you and your squad. The only time it would make sense to choose make things go boom is if you're primarily using explosive weapons to clear trash; it doesn't really provide any benefit when directly attacking large zeds.

Madman Vs. Lockdown
Shoot all weapons 3X faster vs increase incapacitation power by 200%
Generally speaking madman is going to be a better choice. With the exception of single shot weapons, madman is going to be better for almost anything, especially with the passive reload speed bonus in mind. Lockdown is vague in its description, but it most likely means that stumble, stun, and knockdown power are all increase. Submachine guns will almost guarantee stumbles, explosive weapons will almost guarantee knockdowns, etc. Neither of these is going to be incredibly consequential in a game, but generally speaking madman is going to be useful more often than lockdown will.

Weapons:
Freezethrower: Flamethrower-style crowd control weapon. Does some damage but not a lot, can only really be used to kill trash. It takes a bit too long to freeze big zeds to be useful, so its overall usefulness is pretty limited. It's not horrible, but it's certainly not great either. Heavy weapons training improves reload speed.

Killerwatt: Energy assault rifle. Comes with conventional automatic and overcharge firing modes. Automatic mode fires 1 ammunition per shot from a magazine of 50, and the damage is mediocre but it applies an electric stunning effect against targets like an EMP grenade. Extremely useful for initiating and focusing big zeds, but won't have the damage output to kill them yourself. Overcharge allows you to charge up to 25 ammo over a couple of seconds and release as an energy beam with high recoil. Good for clearing groups of trash and has great DPS in lower player count games, but very ammo inefficient; do this too much and you'll run out mid wave. More useful supporting weapon than the freezethrower, with a price to match. Run with a conventional weapon for killing power when you need it.

Other tips:
-The more players are in your game, the less effective you'll be at filling a missing role.
-Cross perk weapons will be considered in your reload skill (i.e. the medic pistol is a cross perk gunslinger weapon, so you get the bonus with tactical reload).