I do think it would be interesting to be able to attach use conditions to attacks (i.e. attacks only available when a character is in water, lava, or both or at 0 energy. Essentially a hyperextension on "dependsUpon"), although I think would be difficult to implement in a manner both effective and understandable.
If someone wanted to, this could also allow 'Limit Break' type attacks for characters at really how health. I don't think I would like that in a tactical game like this, but I could see it being interesting. I guess, moreso, I'd dislike it if a weak foe suddenly got a more powerful attack, although it could be a cool way to have a boss 'power-up' at low health.
As the system stands now, could one write a script that activates when so-and-so's health is at or below a certain number, and at that point give them bonus powers or stats? (Could really backfire if you heal the boss and damage them again

)