Frieren's sheet has to have a "Must fall for mimic chests" weakness on her sheet, but even if you put rules for it on the sheet, would anyone playing Frieren ever want to do anything EXCEPT get half-eaten by a mimic?
I think that's more a roleplay thing then a sheet weakness.
"So you sense magic and it appears to be a mimic" "Well, that's only 99% accurate... and I feel like there's a tome in there so..."
"It's that 1% wherein great discoveries are made!!"
"I like those odds"
as someone who plans to play her, of course I want to get eaten by a mimic
what I would do with it as a sheet power is that if she ends up setting off a trap that was already there, the flavor of that trap may change to being a mimic, or something in that direction
because besides the chest option, she gets herself stuck in other things in a similar fashion, including a falling pile of books
I mean, fair
or if the trap's target is random, she has priority