When you hit a creature with your claw attack they must constitution saving throw of with a DC equal to 8+ proficiency bonus + your strength modifier. If the creature fails it’s saving throw, it must take 1d4 slashing damage at the start of its turn  due to a fiendish wound. Any creature can take an action to stanch the wound with a successful DC 13 Wisdom (medicine) check. The wound also closes if the target receives magical healing.