Dark Carvo will first make two Bosses that must defeat in the past. Do not try to attack them, instead evade them. Once they disappear, you will have a chance to attack Dark Carvo. He will make duplicates of himself and try to attack you. Try to dodge him. He will lose you and stop trying to find you. This is your opportunity to attack him. Grab an egg and keep attacking the Dark Carvo. Once you find the real one, he will get weak and you will have another chance to attack him. Repeat these steps to defeat Dark Raven.