So, not sure if this happened before, but seems like a bug to me.
Onatels special says that the mana steal effect will be removed after Onatel is killed, this seems clear to me: kill Onatel, gain mana again.
I did a raid today where Onatel cast her effect on my Isarnia (and others), on the last turn of the effect, I kilked Onatel with specials, after that I made blue matches expecting Isarnia to gain mana, but she didn’t.
I did notice before that the steal status effect only goes away on the next turn, but I just figured that only be a visual bug, because of the description. If it is intended like this, the description should say “the mana steal effect will be remove the turn AFTER Onatel is killed”, and it doesn’t right now…
Btw, I still won the raid