I found range to be more affective with diamond (e) bolts than melee. My setup was guthans body and legs, helm of neitiznot, dragon boots, dragon square (didn't wanna risk the dfs), rune cbow, diamond (e) bolts, fury, ring of life (for insurance). I used about 12 sharks, but also brought a unicorn along, so without the unicorn it would've been more like 15 sharks. His attack styles change in the same pattern constantly. For me it was something like 3 hits with range, 3 with mage, 3 with melee repeat. So once I went through one round I could anticipate the attack type changes. I brought a whip for the demons afterwards (you need 2 different attack types since they pray), but they're not a problem since you'll be imbued with the power of the stone and thus have 200+ in all combat stats and hp and have a bunch of arma guardians helping you.