this worked amazingly well. didnt lock on, just ran/rolled to his left knee every time, very few of his normal attacks hit you there, and you can punish everything. youll get whacked sometimes (mostly the full slam if you dont dodge it), but if you do dont retreat to heal, that just makes his attacks more likely to hit. just go towards his leg again, but just heal instead of attacking once his strikes go over your head. super effective and i killed him in like 1 minute first attempt with this strat.