i like bosses being hard, but i finally discovered why i feel them so difficult Act 1 and Act 2 actually.

the timings.. you recieve the damage of the attacks before the animation happens,

on act 2 boss first phase one the attack that goes on a straight like, also on the blobs-stains that come from below.
on phase two something similar with the straight like attacks that happen on the moments that you can't damage the boss and with the attack that sets the "land mines"

i hope this gets corrected with time becouse it seems like a problem with the engine as a whole.. you need a lot of time of anticipation to effectively dodge an attack, with normal trash mobs its no big deal.. but with bosses it does count and its notable.