Yeah, unless someone can debunk it beforehand... I'd hate for someone to waste a key by doing the wrong mission because of Nutaku being stupid.
Though if you try with x2 def and x2 healers it'll be a win anyway because it's one or the other. We still won't know which is the correct mission.

Guess I'll just have to yolo and possibly waste a key to find out, because I don't have x2 def and I'm not using off element...