Mergo's Wet Nurse is the last mandatory boss in Bloodborne. You may have more boss fights later, but it depends on your story ending. br Reward: One Third of Umbilical Cord. Eat all 3 pcs after this boss fight to get an alternative Bloodborne game ending. br Good luck and Have a nice game! br br Bloodborne Mergo's Wet Nurse fight. Bloodborne Mergo's Wet Nurse fight tips.