You unravel the corpse and form an exoskeleton from the bones. For the duration, your AC cannot be lower than 17. As a bonus action for the duration, you can feed the ravenous bones with your blood and flesh. You lose 1d6 hit points, and gain twice as much temporary hit points.   The bones crumble away, and the temporary hit point vanish, when the spell ends. If you die while under the effects of this spell, your corpse turns into a ghoul.