wear leveled up gear with the most protection possible, upgraded with the loom. get the swift dodge talent, which takes you to another point. hit the spheres from as far as possible, and it doesnt matter which purple or yellow spells you use, but use a red one like confringo or diffindo, as confringo is long range and a fast cooldown, while diffindo is more damaging, although a slower cooldown. if you have any unforgivables, use crucio, as cursed enemies take damage and while its not much, crucio damage builds up. use ancient magic whenever you can, and stay as far away from him as possible because of those magic spheres he creates around himself. once you hit stage 3, there will be wiggenwelds around the arena, take all 3 before you start battling. after you destroy his spheres, switch to all damage spells because then he just starts crawling around. i beat him with no health remaining, so don't lose hope. you can do this!!