Gonna be honest, I tried playing against the imps, but there is no way to defeat them unless you got the kitsune transformation and like stockpile a bunch of those attacks and get really, really lucky to be able to use one. When you transform into an imp, the only things you can do is knockback an enemy (basic attack no longer works) or wait till game over due to running out of abilities. Imp transformation is bad until basic attack works or there is some kind of counter to get these imps without using everything you got.