tip for the fight:
Destroy the statues. Elements will be able to hurt him.
Oooooooooooooooooooooooh fuck. That changes everything. I'm a moron for not thinking a bit more about the layout of the room and why certain things were obviously there. Thanks!
or just blind him over and over while your melee takes him out.
Witchcraft destroys this fight, summons destroying + blind
I'm not having much luck with status effects on him so far, but I'll keep that in mind.