The Star Magician from GS2. He has 4 balls that surround him, one attacks with thunder, one selfdestructs and does massive damage, one blocks almost all damage to him for the turn and one heals him 1000 hp. And once you kill one he can use an ability called Mystic Call to summon a random type of ball. the easiest way to kill him is to keep killing the balls over and over again until only the thunder balls surround him and then directly attacking him, and that's really hard to do and takes forever.