Just going through NG++, and tried to bait the Mimic to help out for the Fire Demon on the way to the Smoldering Lake. That Mimic single handedly destroyed the Demon. They got locked into some sort of animation loop where the Mimic kept getting it's large golf-swing kick attack in, staggered the Demon, and the Mimic went straight for the kick again while the Demon tried to wind up for an attack before getting staggered out of it again. Yep, that Mimic stagger locked and killed the Demon for me, all by itself. Best Mimic ever.