Ok just so u know idk how to put up screenshots on a mac so just try to understand this.
Ok once you skip all that stuff and you get to the 2 defenders (anti CC units) go into the big tub of water to the right (once your facing the acute angled wall) and go to the right where the rock meets the metal pillar. Just walljump up that to get ontop of it and run to the rock! Now your behind the entrance to the quest guys place. Now you can go and kill second boss first! (you still need to kill the normal way to do first boss though).
Idk if this was posted before but if it is then please, I BEG OF YOU! PLEASE FLAME ME!!!