Hexblast (Spell) breaks Demon Form all of a sudden. Worked fine past couple days.

Hexblast is a spell, and it suddenly instantly breaks Demon Form. It started happening a couple hours ago.

Before it diden't, and i've played with Hexblast for a couple days now with 0 issue. NOTHING was changed on the character between it working properly, and the bug starting to happen.

Solved: Hexblast was getting too many levels from Demon Form, and that increased the intelligence requirement beyond what the character had.

It showed the spell animation when cast, and disabled Demon Form.
I assume it did default attack instead (An attack, which cancels Demon Form), but then that would make the spell animation a bug?