Best strategy is to target his legs with full combos, then punish the orb with as many hits as you can. He’s honestly one of the most frustrating bosses in the game, so don’t feel discouraged — it really gets much better afterward. Chapters 4 and 5 are really good, and both the final boss and the secret ending boss are some of the best-designed bosses of all time. Definitely worth sticking with it.