Undying

This spell can only be cast as a reaction if the PC takes devastating damage (enough to cause unconsciousness or death). Upon casting, a bright golden light flashes out in a 30 ft. radius and the caster is instantly saved from death or unconsciousness and returned to HP determined by rolling half of their hit dice. For one round after casting, the caster has +1 to their AC.

This spell can only be cast once per long rest.