For those who don't know, Epic Volume III Book 3 Chapter 10 is bugged, you can not advance the quest while in combat.
And you enter combat against mobs that do not die. When you get them down to ~20%, they turn green then heal and aggro again.
To finish this quest, pull the smallest group possible, run to the back of the area hit them until one turns green, then run about 15-20m away so that after the green mob heals, it wont aggro on you.
Basically space them out so that there are none aggroed on you and you are standing near the quest finisher.