Original Sin
You have access to a miraculous self-regenerative ability that automatically reattaches severed limbs and heals other traumatic bodily injuries. In exchange, your body hungers for raw, magically-imbued flesh every time Original Sin activates. Regardless of activation, you feel the need to eat once a month. If you do not sate your cursed hunger, you will be inflicted with a permanent nausea that turns to a crippling sickness. Your body then steadily atrophies, and you will have roughly a month to eat before your body wastes away.