Can only be done on 2nd Playthrough. Recommend farming 5x Adamant Armor on first playthrough, and 5x Cursed Rings on 2nd Playthrough. Wearing the Armor and Rings, all of his damaging attacks heal you, and you are immune to most of his status inflicting attacks. Very rarely he will normal attack and 1 shot someone, but that's easy to raise/cure since it's so rare.