You can also press CTRL + arrow up/arrow down to adjust our camera field of view more up and down to view more of the boss accordingly. I found this to be a big help when fighting.

Also worth checking your connection speed - I play from UK on US server (Aether DC) and there is a noticeable 1-2 second delay for Boss moves to show on my screen compared to more local folk so I learn to move with the group rather than watching out for telegraphs. If everyone is suddenly running to the other side of the boss arena, I don't stick around to see why