Cranial Insurrection

You let out a screech of intense proportions, and reach your hand toward your target. If the target has less than 40d8 health, It's head is removed from its body and flies to the sky. The target is instantly killed. If it does not have a head, the heart of the creature is instead removed. If it has neither, the target instead falls down dead, as its soul was ripped out. This spell can only be cast once per 1d20 days.