Edit: Fixed bugs are marked with fixed, new/unfixed bugs are marked with unfixed/new/unknown I haven't personally verified all of these so feel free to reply with corrections
Zombies:
Their leap-and-bite attack is completely bugged. If your shield is down, they'll stand next to you and perform normal slash attacks while you're unable to move or shield. If your shield is up, they'll land on the shield and start biting, but they'll end up getting bumped away and biting thin air instead. unfixed
Zombies can also do their leap-and-bite move through a forcefield, resulting in no damage to the knight while they are held immobile. unknown
Lichens:
Toxigel and (giant) lichen colonies' spin-thorn attack melee damage happens before the animation. fixed
Darkfang Thwackers:
Spin attack is not telegraphed with a red attack marker. Looks just like a dodge until half your health bars end up scattered on the floor. fixed
All Gremlins:
Dodge move has no rate limit or cooldown, and they will dodge from just a regular non-attacking knight, making it very difficult to catch up with them and actually kill them, even with a reasonably fast sword (eg acheron). unfixed
All Gremlin Menders:
Will still occasionally forget their oath and perform a chain of swipe attacks in some situations. fixed... supposedly ;)
All Gremlin Bombers:
Can occasionally drop bombs through solid obstacles. unfixed
Tier 3 Wolvers and Alpha Wolvers:
Teleporting wolvers will block player movement before the wolver reappears. (ie, the space where the wolver is about to appear will be impassable by knights) fixed
Wolvers can teleport unexpectedly while performing attacks. (ie, an alpha wolver can teleport in the middle of performing a three-bite attack) fixed
Wolvers can multi-teleport in some situations. (ie, they'll teleport, and then immediately re-teleport somewhere else) unknown
Wolvers and Alphas can teleport while frozen. unfixed
Wolvers and Alphas can teleport outside of walkable map bounds. unfixed
All Wolvers and Alpha Wolvers:
Can sometimes turn to follow player while in the middle of an attack, rather than attacking in a straight line. fixed
Retrodes:
Retrodes can perform a melee attack immediately upon spawning which is nearly impossible to dodge or block. fixed
When attacking from off screen, the sneeze animation does not sync up with the line of explosions. unknown
Greavers:
Greaver status clouds can penetrate otherwise impenetrable obstacles. This can lead to situations where a solo knight is permanently frozen in place by a group of greavers who are inaccessible to attacks. unfixed
Jelly Cubes:
T2 and T3 jelly cube's ground spike attacks can complete after the jelly cube itself is dead. unfixed
Tier 3 Polyps:
When interrupted at the exact moment of attack, polyps will sometimes shoot only a few thorns rather than none or a full simultaneous volley. unknown
Kats:
Kat lunges are highly unpredictable and unintuitive when their path is obstructed. unfixed
Slag Guards:
Will damage knights standing directly behind them when initiating their charge attack. fixed
Attack telegraph is shadow/purple, but attack damage is pure normal. unfixed
The brandish-line charge attack explosions can penetrate the slag guard's shield, and the resulting explosions will deal damage/status to the slag guard even when the guard is facing the player. unfixed
Lumbers:
Lumbers attacking through barriers will cause knockback but no damage. unfixed
Lumbers don't take damage when attacking while cursed. unknown
All monsters:
Can attack through switch gates in IMF. unfixed
Can attack through locked gates in Decon Zones. unfixed
Gun Puppies:
Gun puppy bullets can spawn well ahead of the gun puppy itself. Sometimes a bullet won't even spawn aligned with the other bullets in the same volley (T2). fixed
Shankles:
Can sometimes stop moving entirely. unfixed
Wisps:
Can appear in "vulnerable" state while moving and invulnerable. unfixed
Chromalisks:
Electrolisk spit wads can continuously shock the player, leaving them unable to shield, move or attack. unfixed
If anyone knows of other bugged attacks, post a reply and I'll be happy to add them here.
The scuttlebots bullets may go thorugh the purple barriers on Ironclaws Factory and damage you.
Lumbers that attack behind a barrier will not damage you but still push you back. Easily seen on left room of Royal jelly palace.