Curse Magic

Curse Magic (魔法のを呪う, Mahou no Norou) is a type of Magic that will possess a person's blood vessels and turn their Rukh black if it is white. They will then be reborn as a new person because there exist no one without darkness. Isnan stated that if you try to oppose the change, Solomon's Rukh and the Black Rukh will destroy each other in the person's body and their flesh will rot.