• Note that this guide was made with my experience using dual katanas. Some punishes listed here might not work if you're using a different weapon setup (the primary concern being the speed of your attacks); however, it should be pretty easy to adjust the punishes listed in this guide to suit your own needs.
  
• This sounds odd, but you should take off some armor until you're light-loading. Light rolling is incredibly valuable for Malenia, because usually, a single lightroll will get you completely out of her range, regardless of your timing — thus allowing you to space her out incredibly easily, and avoid getting roll-catched. Some dodges in this guide may not work if you're not lightrolling.
  
• If you have less than 1,600 HP (and this is generous), and aren't doing a challenge run, I recommend either grinding runes to level up Vigor or respeccing more into Vigor at Rennala.

So! You're fighting Malenia. Well done! It's been a long journey here, but you're approaching the end now, and— oh. It seems you are dead.

Malenia is not like the other bosses you've fought thus far. This is for a few reasons, some of which are good for you and some of which are bad for you. Let's start with the good news:

• She is very, very easily staggered [hitstunned] — easier to stagger than you are, in fact. A few of her moves give her super-armor, but in any other circumstance, anything stronger than a dagger will stagger her.
  
• She's very patient. In her first phase, she might sometimes dash at you, but otherwise she'll give you the space you need to heal and prepare between her chains. In phase 2, she's a bit less patient, but you still have time to heal if she's just running at you.
  
• Her range is very short, and she doesn't cover much distance with most attacks — as such, you can, and should, space her out while she attacks. Spacing her out saves your stamina for the important things (namely, panic rolling), means you don't have to perfectly dodge every attack; and most importantly, conserves valuable brain energy.
  
• Her attacks are extremely well telegraphed — she moves smoothly, all of her delayed attacks have clear audio & visual cues for the timing, her fast attacks are telegraphed clearly and distinctly, and many subtler cues divulge info on what's going to happen next.

And now for the bad news:

• She heals after every single hit she lands. How much depends on what attack she hit with (in particular, her pierce attacks seem to heal her the most), but she'll heal even if she just hit your shield. This means you can't afford to facetank her, as every hit you take makes you lose progress. And therefore, unfortunately, to beat Malenia, you will have to get good (don't worry, though — I'll teach you how!)
  
• She has very long, flowing attack chains, and it's somewhat hard to identify potential mid-chain punishes. The chains are long enough that your statuses can wear off in Phase 2, should you not interrupt them.
  
• She can interrupt your punishes by dodging away or blocking you, and she can promptly counterattack. You can usually get a second attack in after a stagger, though — the second attack will interrupt whatever attack she was planning, but she'll dodge or block during or after your attack, meaning you cannot get a third attack in. Remember this.
  
• She has Waterfowl Dance, an attack that is very difficult to dodge if you don't know how.

Unlike other bosses, I would say that Malenia is more a test of strategy than of skill. Malenia doesn't have that many attacks where you need to time your rolls with each swing (save for Waterfowl, of course) — rather, you want to script the battle by using good positioning, rolling in the right direction, and calculating your punishes.

Here's what you should do:

• Space Malenia out whenever possible; walk, sprint, or roll to stay just out of her range, but remain close enough that you can punish her.
  
• Be patient, but don't miss a beat. Especially in Phase 2, your statuses will wear off if you're not keeping up, so learn when to stand back and when to close in.
  
• Keep an eye on your stamina; if you're about to run out, play defensively for a moment while you recover it.
  
• Don't heal too early; if you're low, wait to pop your flask until you're certain you're safe — Malenia will not hesitate to stab you should you insult her by healing in the middle of her chain. A good time to heal is when she's walking, and you're a decent distance away.
  
• You should usually check that it's safe to do a follow-up attack in your punish (e.g. whether she's staggered); sometimes, Malenia will start a move that has super-armor before your next attack and thereby avoid getting hitstunned, so watch before you commit.
  
• I would recommend waiting to pop your Physick until Phase 2 during her Scarlet Aeonia — as Malenia is more dangerous in P2, it's more important to do damage quickly.

This currently covers most of the attacks I was able to come up with a name for. Info on some other attacks, as well as some other intel I felt wasn't worthy of inclusion here, is in the "Miscellaneous attack intel" section.

(Wherein Malenia hops into the air and lunges)

Jump and start a jump attack as she starts falling (the window for this is very long). Your lower body is invulnerable while jumping, so you're actually safe doing this; however, if you jump too early, Malenia will have time to angle the piercer upwards and you will get bopped.

The jump attack won't stagger, since she has super-armor, but if you're in Phase 1 you might have enough time to get a second hit in, depending on your weapon. In Phase 2, she might follow up into an Air Stance and thus dodge your second attack, but a whiff is still safe here.

(Wherein Malenia steps back slightly and holds her left hand out with a sound cue, and then lunges shortly afterward to grab you, impaling you if successful)

It seems Malenia can't grab you if you're midair, so this can be easily jumped over, just like the piercer. The sound cue is distinct from other attacks, and easier to catch than the visual cue; jump when you hear the cue and start a jump attack, then follow-up. If you're too late on the cue, though, just roll.

This can flow into other moves in P2, but she has no super-armor here — thus, a jump attack will end the combo there.

(Wherein Malenia's prosthetic clicks and then she rushes in, slashing three times and then a slightly delayed fourth time.)

Roll generally backwards (alternatively, roll diagonally forwards if midrolling, or jump backwards), and subsequently keep out of her range.

This is sometimes the end of her combo, and there are many telegraphs for that. If she won't combo out:

• The first prosthetic click will sound slightly different; there are several possible "non-comboing" click sounds you have to keep track of, though. This is the earliest cue for a non-combo Quickslash, but the hardest to catch.
  
• She will dip her head much lower during the dash. This is the second-earliest cue, and pretty easy to catch.
  
• The second click will sound different, and the fourth slash will be much more delayed.

In any of these cases, punish with a jump attack after the delayed fourth slash (or a heavy attack, whatever you choose). You can even flex by jumping over the fourth slash, exploiting the lower-body invulnerability for style points.

(Wherein Malenia attempts to kick you, stunning you if successful)

This attack has a distinct sound cue — a wooshing sound as she starts. To punish, walk backwards for a brief moment; then, roll straight towards her as she kicks, intentionally bonking her (you'll end up roughly behind her, to her side) and roll attack.

Note that she has some super-armor during this attack, so check if she's staggered before you follow up on the punish. You also, unfortunately, might not be able to punish this safely if you have a particularly slow weapon.

Malenia always does this if she gets within range after dashing towards you; as such, it's a free punish.

(Wherein Malenia lunges a short distance and slashes afterwards)

Roll backwards in time with the slash, and then walk backwards to easily avoid her next attack. Note that she has super-armor during this move.

(Wherein Malenia's prosthetic clicks and she poses her sword backwards on the ground, slashes up after a delay, and then slashes down after a shorter delay)

If you have time, attack once as she starts this. Then, dodge diagonally in time with each slash, and punish at the end. The first slash takes a little longer than it looks like, as the sword stays underground for a while even as she starts flying up. In my experience, this isn't enough to catch my rolls, but keep it in mind.

For reasons I don't know, she will occasionally not do the second slash at all — her prosthetic will click midair and she will gently return to the ground.

(Wherein Malenia enters a crouching pose with her sword behind her back, accompanied by a prosthetic click, and — after a delay — virtually teleports to her target and does a horizontal slash followed by a ground slam)

Malenia rarely does this attack when you're far away from her. You can sprint backwards to exit her range; alternatively, when she "warps", wait a split second and roll left, and then forward. Punish accordingly.

In Phase 2, the ground slam will create a flowerburst [delayed circular explosion]; gather some distance while you wait it out.

(Wherein you will finally go to bed in a fit of rage at 5:28am)

I have a full guide on this!
https://steamproxy.net/sharedfiles/filedetails/?id=3285669116

It seems Malenia only starts Waterfowl when she is recovering from hitstun, or from her own endlag "after" a combo ends. She can also only do this while she is below 75% health or so.

(Wherein Malenia rises into the air, and crashes into the ground after a delay, creating a flower explosion shortly after. Phase 2 only; always at the start of P2 and also when low HP)

Sprint sideways until the aeonia bursts. Yes, that's it; this works at any range. She has very, very slow horizontal tracking during this; if you can get right next to her, you don't even have to sprint — just circle her and walk away gently when she lands.

If you want to dodge this the old-fashioned way, there's a visual cue — she starts moving downwards just before she crashes; roll sideways as you see that, start sprinting away, and then roll again in time with the aeonia burst (try to time it!)

This has a lingering AOE — watch for her to start getting up before you run in. Aeonia also gives you plenty of time to heal and buff up, so use that opportunity.

(Wherein Malenia rises into the air with her sword raised. Phase 2 only)

Malenia will decide to do one of two attacks after a while depending on how close you are; if you're right next to her, she'll swing down and create a flowerburst, but if you're far away, she'll swoop down with a slash and follow up with a Quickslash that always comboes.

If you have time, get next to her so she does the flowerburst swing (this is the easiest one to punish), and dodge diagonally forwards. Then, you can wait a bit to recover some stamina before doing a jump attack punish.

Otherwise, roll diagonally left as she swoops, and you can attempt a punish by circling clockwise and jump-attacking as the Quickslash ends. This is risky, but safe if done correctly.

(Wherein Malenia rises into the air, sweeps down with a slash, and then flows into a piercer)

Dodge into the sweepslash, then jump attack about 3/4ths of a second later to punish the piercer. Sometimes, the piercer will be more delayed than usual — however, she will also not go nearly as far when this happens, so jumping is still safe as long as you have distance (which you should).

(Wherein Malenia rises into the air and forms a tornado beneath her, sends several flower ghosts out to attack you, and then lunges at you with a piercer attack. Phase 2 only)

Sprint left to dodge the first two ghosts (or walk for just the first one). Then, time a leftwards roll to right before the third ghost's delayed attack lands. Continue spamming left-rolls until the last ghost finishes attacking, at which point you should rush at Malenia, who will conveniently be just to your right.

These are Malenia's dodges, etc. that she can use to avoid attacks or interrupt your comboes.

Wherein Malenia strafes to your left and slashes at you after a brief delay; just roll away, or even walk. Note that the Nagakiba is long enough to sometimes catch this and stagger her out of it.

Wherein Malenia strafes to your right, and sometimes slashes after a brief delay; just roll away.

Wherein Malenia elegantly dances backwards, retreating. She's slow enough that you can chase her down to get a free hit if you have time - and she has no super-armor during this, so she'll be hitstunned.

Wherein Malenia quickly dashes backwards. She can follow up with a Quickslash, a piercer, or etc.; just respond accordingly.

Wherein Malenia blocks your attack and then counterattacks. Immediately roll backwards twice as soon as possible; one of her counterattacks is extremely fast, so you don't have time for trying to react elegantly here.

Wherein Malenia dashes towards you while you're at a distance. She can do this multiple times if she doesn't catch up with just one (especially in Phase 2), and (as mentioned earlier) will always do a kick attack if she gets within range after dashing. That's a free punish, so always keep this in the back of your mind.

Wherein Malenia does a large dodge to the side when you fire certain projectiles at her. She'll often start dashing after she does this, which means that just shooting random projectiles at her can earn you a free punish. HOWEVER, she can also choose to start Waterfowl out of this, so use with caution.

Here's some other miscellaneous intel on her attacks or other actions, especially the ones I couldn't name.

• Malenia often ends her combo on a generic, low slash from left to right (from your perspective); this is a free punish.
  
• Malenia likes to do either Dash, Quickslash, or Piercer out of a generic, diagonal double-slash from down-right to up-left.
  
  • If she hangs after the second slash, she'll always dash. You may be able to use this time to charge a heavy attack, and have her run right into it.
• The attack where she quickly slashes up and then does a ground slam can be avoided by simply walking backwards, provided that you're already out of range. This makes for a trivial punish.
  
• Her Scarlet Aeonia actually has limited range — it's about the distance between her starting position in P2 and the far end of the pond.
  
• When Malenia is walking gently forwards or sideways, you may be able to punish with a running jump attack before she can attack back — depending on your weapon. This seems to be slightly riskier when she's walking at the very start of the fight, however; perhaps she's able to do lunge attacks and dashes in that walking state at the start? Or perhaps she loses her patience by the time you reach her?
  
• When Malenia is sprinting in P2, she'll usually do a lunge slash once she gets in range.

When you fight Malenia as a Furled Finger, things become ever so slightly more complicated for a few reasons:

• Other players attacking may cause Malenia to unpredictably sprint, roll, or change targets.
  
• Lag may result in a few shenanigans.
  
• You may end up further than normal from Malenia at the start of P2 (Furled Fingers will start P2 where they were when P1 ended).
  
• The host may get instagibbed by Waterfowl Dance or Aeonia if they draw her aggro at a bad time.

Here's my advice:

• Don't let your guard down when you've attacked her recently — always be ready for her to spontaneously switch to you.
  
• If your host is particularly laggy, time a roll for the Scarlet Aeonia burst in addition to sprinting sideways — in extreme lag, Malenia sometimes throws curveballs with Aeonia.
  
  • Also, jumping to punish the generic piercer may not have a safe follow-up anymore if the host is particularly laggy (usually, proper timing for the jump will avoid this, though). In P1, you might want to do a roll attack instead, or simply do a one-hand hit if you're dual-wielding; however, in P2, the jump attack is still earning you a free punish, while rolling can't punish if she comboes out.
• An idea is to keep Fan Daggers handy to draw her aggro when the host is at risk; you can get her off the host while Aeonia is starting, or sometimes at the very start of Waterfowl.
  
  • You may also want to lure Malenia towards the back(?) of the arena during Phase 1, so that you're close enough to aggro her while she tries Aeonia in P2.

Also of note: don't feel bad about soloing for other players, even if you're worried the player might regret it later — because if they're summoning you, they've probably already made up their mind.

If a Furled Finger is already attacking Malenia (as in dodging her actively), and you want to help by getting a melee hit in, only do it if you're sure you'll be able to land a follow-up. If you land a follow-up, Malenia will become stressed and dodge away or etc., buying you time — but if you fail, perhaps because you got interrupted by being hit, she won't stress out and will instead retaliate instantly, quite possibly with Waterfowl. This puts you in danger, but it especially puts your ally in danger (they may have been in the middle of an attack), so be patient!

• Malenia's prosthetic clicks when she's adjusting her grip on her katana. With the Quickslash, it clicks because she's holding the katana higher; with the piercers, it clicks because she's folding her hand down to straighten her sword.
  
• Malenia cannot be killed by critical hits, nor while she is recovering from a crit, due to a band-aid bugfix that was made to prevent her from dying in Phase 2 instantly.
  
• Very rarely, Malenia will glitch out at the start of Phase 2 and refuse to do Aeonia, instead doing whatever. It seems this may be caused by status effects like frost or bleed proccing as she transitions into P2.
  
• Malenia can lifesteal off your corpse as you are dying. This doesn't really matter that much as a Furled Finger, UNLESS you die to the tornado of Tornado - in which case she will heal straight to full.
  
• Speaking of Tornado: having low poise is helpful, because you'll then get knocked away from the tornado rather than getting stunlocked to death.
  
• Technically, the "flowerburst" is butterflies, not flowers; however, "flowerburst" rolls off the tongue easier.
  
• As for proof that Air Stance is a stance and not two separate moves: while soloing for a particularly laggy host, I witnessed Malenia glitch out and choose both attacks simultaneously out of that position.
  
• If Malenia is standing on the elevated ground around the edges of the arena, and does a Piercer attack while her target is on much lower ground, she'll end up falling - which can actually result in minor goomba-stomp damage.

Things that I've yet to figure out. If you have an answer, please let me know in the comments!

• In P2, does the Piercer have any cues for whether or not it'll combo?
  
• Does the generic diagonal double-slash have any other cues for what attack will come next, besides the one where hanging on the second slash means she'll always dash?

I hereby release this work (How To Solo Malenia, the Fancy Way by MutantVampire) under the CC BY-SA 4.0[creativecommons.org] license.

in short try mimicry
but attribution required ahead
and then let there be sharing [under the same CC BY-SA license]

Anyways, if you have any feedback or questions, please let me know in the comments!