WE DON'T BREAK THE RULES WE ONLY BEND THEM SO IT'S NOT CHEATING!

Combat:
Abyss Odyssey is a game where the player must over come enemies that often times out number you 4:1 or more and from time to time the a.i. will simply refuse to give you a break. On nightmare difficulty in co-op or single player they don't fight fair either! I have often found myself stuck in a situation where 4 enemies have me in a corner and will just combo you to death!
(literally from full health to death without stopping)

Traps:
Most traps in the game are easily avoidable, some are ridiculously placed so that the trap is hindered or blocked by wall making you think "wtf was this dungeon designer doing?". However, on the very rare occasion maybe 1/1000 you will find a trap that is literally impossible to get by without losing half of your health...

Warlock:
So you've finally managed to get past all the ridiculous battles and tricky traps and made it to the warlock only to die from his deadly 2v1 (or multiplayer 3v2) combo attacks... just great....

Well it's not a 100% fool-proof strategy but here are some cheap tricks to make your journey a little less frustrating:

1) Shrines-
Probably the best relief in the game; the trick to full healing is simple.
a) Clear a dungeon floor of all the baddies so they won't get in your way.
b) Drop all your items + Captured monsters via the inventory menu
c) Go find a trap (there's always a trap) and let your character be defeated (not your soldier)
d) Pick up the Monster Soul + all your items and viola! you now have full HP on both your Hero and your Captured Monster
Note: not dropping your monster soul before you die will result in loss of monster soul, not picking up said soul before you revive will prevent monster soul from being fully healed.... sometimes souls will appear invisible after you drop them due to a glitch so you'll just have to look around for a "Pick Up'
Note: This trick will deplete all of your mana in exchange for full health so it's best to already have a captured monster or expending your mana before usage!

2) Merchants-
These guys are great, every time you see one check him for health potions (they're relatively cheap sometimes 600-1400 gold for a healing potion which is WELL worth the price since you'll typically make 2-3k per floor.

3) Capturing Monsters-
Probably one of the most important aspects of the game, your level determins which monsters you can capture but that doesn't really matter, going into combat with ANY monster soul is better than going into battle vanilla, keeping a monster soul to absorb damage for you will save healing potions which you will want to do as often as possible! (capture is as simple as hitting basic attack + special attack at the same time while your mana gauge is full)

4)?-
When you go into a ? it's typically best to have a captured monster selected... if you have your Hero selected and lose the battle you will lose HP on the currently played avatar... which could mean your Hero (ouch).... while most of the ?'s are easy to win I've found on multiplayer even the "Easy" difficulty '?'s' can be a good challenge

5)Traps
From time to time you can exploit a trap to your advantage (my favorite are the Holes that can 1-shot enemies) if there's a trap and a group of enemies on the same screen try keeping the trap between you and the enemies, they aren't too smart when it comes to traps and I've easily killed whole enemy waves before without landing a single blow via 'Traps' exploits... be creative, use the dungeon created to kill you to your own advantage!

6) Don't fight fair!-
Enemies in the dungeon will not fight fair, they can instant block (they literally will put up a shield block faster than humanly possible and combo you into the ground while you are just trying to regain control of your character...if you try to block they will instantly throw you and continue the cycle: They don't fight fair--WHY SHOULD YOU? Each of the heroes and many of the enemies that can be captured have very cheap spammable abilities.... if you get the opportunity to knock an entire enemy encounter into a corner there's nothing shameful in Abyss Odyssey at taking full advantage of a combat situation with some nice well-placed CHEAP ATTACKS (think street fighter)

7) Leveling up-
Not necessarily the most important aspect of the game, however going from lvl 1 to level 20 will significantly increase your hp by around 500-700hp which is quite helpful at times, further leveling will give diminished returns but is still helpful (more hp means more hits you can absorb)

8) Before the warlock-
At this point if you don't already have full mana you may as well go ahead and kill off your character, use your soldier to pick up all your items + summons: (there is a revive shrine just above where you will fight the warlock) I typically enter the warlock room while solo with no less than 3 Large healing potions (you'll want them) however most times on multiplayer this isn't an option.

9) Battle with the warlock
No matter how you swing it; this is no easy fight! The warlock will spam his flying fish while his teammate(s) will pummel you into the ground. The best solution to this is have a lot of health potions, a good monster summon and full mana (even if you can't capture him).... and be ready to get down and dirty with it.....I usually find it's easiest to kill the Large Ninja Dog looking thing first since he's more likely to make a series of direct attacks. Focus all your damage on 1 target at a time, trying to kill them both will only weaken you faster the fight is a little easier once you take one down. However if you get the chance to use your capture spell and hit both the warlock and his ninja dog at the same time go for it, a full shot will deal nearly 1/3 of damage to either or both!

10) you've won!-
Okay so you beat the warlock and his ninja dog and smashed his mask into oblivion and saved.... "the world?" no, just saved your Phat Lewtz! At this point there's only ONE more tip I can give you, once you reach the after boss room where everything is all gray.... switch characters! I don't mean switch characters and go and play a different character, by all means keep playing the character you are currently playing if that is what you fancy... but switch between characters at least ONCE as this will restore you to FULL health which you'll probably need / deserve at this point (I don't know why the game doesn't just auto-heal you... i mean you just saved.... your loot, after all)

Feel free to add guide suggestions if you find any cheap tricks I'll be happy to add them! Good Luck!