First of all,have lx or ox.When he gets 1 lifebar or less,freeze him when he toutches the ground(this has to be timed corectly)then, somtimes when you do this,he will go up and he will shoot purple thunder from 1 side to another.To doge this,you have to have good timing.Look carefully,the ball of thunder will stop shooting some time, when that happens,QUICKLY dash under and past him.If you on't do this in time, he will start shooting again.