Boiling Blood

You attempt to cause the blood within a creature with a vascular system to heat to the point of boiling. The target must make a Constitution saving throw taking 2d10 fire damage and 2d10 necrotic damage on a failed save, or half as much on a successful one. On each of your turns, until the spell ends, you can use your action to cause the creature’s blood to boil again, targeting the same creature which must make a new saving throw.