I found this too and I'm a long way from great at these games. Seems odd people have trouble with him.
I think he is just a bit luck based depending on how agressive his minions are to you.
When multiple of them attack you at once it can be really hard to dodge them. And when you get hit once chances are another one attacks immediatly after.
And some of them are off-screen almost everytime because you can't really monitor them all at once, while attacking R
om