So about Fyodor's ability we've only ever seen him use it on people and the only info we have on it is that it can like blow their brains up (since that's all we've seen it do iirc) and that it's named Crime and Punshiment.
As we all know Fyodor has a weird type of a god complex i guess you could say?? Basically he has decided he has the power to pick who should and shouldn't existed and picked ability users as the ones that shouldn't. Except himself. (from what i can understand)
He believes he has the right to pass judgment on such a thing as someone's very existence and punishes people based on whether he perceives them to have a committed a crime or not.
You getting what i mean??
From its name and what we've seen of it so far i think Fyodor's ability works in a way similar to court except he's judge, jury and executioner.
He is the judge of whether someone's life has been a sin or not, in this case ability users, and then executes them accordingly.
So in short how i perceive Fyodor's ability is that it only works on people Fyodor sees as criminals according to his own morals and ideals. Thus he can use it on any ability user and on only those non ability users who he sees as wrong and "evil" to put it in a very very very simplified way.
It's definitely more complicated than whether he sees the person as "evil" or not but yeah basically this is what I think it is.
Which also ties into my theory that Fyodor CAN'T use his ability to break out of the water tank area thing because the walls themselves are not something Fyodor does or CAN ever perceive as criminals and thus cannot blow them up. Even if he blames Dazai or hell even the guards for losing so easily he would only be able to attack them and not the gates.
Therefore, Fyodor is gonna die.