To add to this, it's the layering that tends to get me. Boss is going to attack in a checkered pattern...now half of that is going to be covered up by a half arena attack... now half of that is going to be covered up by a left to right tidal wave...now the boss is going to slam down on your location. Oh and this is a storyline dungeon boss, hardcore bosses now add DDR to their attack patterns.
Forgot to mention all the visual flair going off during it.
I didn't struggle too bad this expansion but it was definitely more irritating than previous ones.