I havent played in over a year but the way I used to do it was clear everything from that upper level. Every mob. I would try to keep the boss in a general area to drop his crud. don’t stand in the crud he drops in the ground. Try to keep him CC’d. Same with the boss that comes after, don’t stand in front of him when he does a certain spell that I can’t remember the name of atm. Use that entire upper level to move about if needed.