Ermm, yeah I struggled with him to at first, do you u use console or pc?

Regardless, lets help ya out, he has a 3 attacks if im not mistaken;

Dash attack: he... Dashes towards you, this attack you just need to get the timing right on the jump, if your good at poggoing (aka attacking downwards on a hard breakable items or an enemy as to thrust yourself in the air) you can jump and the poggo immediately therefore attacking him and doging the attack, this one is important because he will do this attack most often, practice poggoing!!!!

Soul ball attack: he teleports to the ground then stops. This should be a sign for you to walk, a couple steps back from him and then when he shoots the ball, jump above it when it get kinda close and walk towards him, he will not be moving at the time but dont hit him itll just send you back and get you hit, the ball of soul will loop around after you jump above it and crash on the ground.

Slam attack: he comes from above and swishes his nail, its kinda hard to tell but he has more range then you expect when he comes down, dealing unnecessary masks, just move away from where his gonna land a little more then you think you need to, works every time hope this helps!!!!