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It definitely isn't her fault – some creatures work perfectly with her and never crash the game, not even once.
(But the combination of a regular fear attack and poison might be the issue.)
It's an interesting situation.
I removed the animations, replaced them with a link to the Black Knight, and the crashes still occur as before, even though he already had the appearance of a Black Knight.
I reverted everything back. I removed the venom ability. Immediately, the battles that were previously crashing (and if he crashed in one load, he will definitely crash in the same place if you reload) stopped crashing, and everything became normal, except that a good ability is lost. So, I was wrong to blame the animations.
I added the venom back, removed the fear attack. Everything is normal again.
Judging by the fact that there is a creature on the Psathea website, the Maenad, which also tends to crash the game when it has fear and regular poison, it is likely that these two abilities are incompatible.
By the way, the Tormentor also has poison and crippling wound, and it also tends to crash the game. Moreover, they can all crash the game not necessarily when attacking, but also when taking a turn, when attacking undead, and so on.
Perhaps poison and venom are buggy and don't work well with other abilities.
Added after 10 hours and 59 minutes
Well, does anyone have any ideas about what can be done with poison so that we don't have to give it up?
I have a hypothesis that in the CreatureVisual DamageEffect, there should be , and not Necrohit2. And there are good reasons to believe that this is the case. So, if this is confirmed, Psathea will need to make the same change in the Tormentor and Maenad so that they don't crash the game.
It still crashes, but a little less often. It seems that the incompatibility of fear and poison is indeed the issue.