Try hell belial and you know what is hard
level 60 and still die many times.
His 3 hit combo (smash) and his meteor is the killer.
3 hit combo is easy to avoid just run the out of the way of the green circle for 2 times ( left and right ) and the last one ( middle )
for meteor, it's all about avoiding and luck, if you stand one spot and he mass spam that spot, just pray it doesnt 1HKO you