As a Lvl. 87 Luster I've had mixed but I think majorative success in not incapacitating too much on the Ultra Hard Urgent Quest - The Face of the Abyss. Sometimes 6-8. Mostly 3+/-. Which I assume or am hoping this would be considered decent/acceptable 12-Man MPA (Multi-Player Area) performance contribution. By far 80-90% of the times I've, and seemingly most everyone else, died "en masse" is during the "Second Phase" I guess you would call it. Where you fight the hole for a face stick thing with the mini-universes like where Dark Falls Gemini's big ball things would be. Regarding what to do and not to do. Or rather important when/where to be and attack is where I'm hoping to learn some additional tips and strategy.
So far I think for the first and third (last) phases attack the sides of the eyes. Not directly on. Seems to help survivability. Hide behind, everyone else, the stalagmite/glacial like things when the ground gets "windy looking" in the second most deadly phase. I think I'm starting to get a feel for when what hand/arm is gonna come down in the third phase.
Curious what if any other pearls o the wisdom there might be to further enhance my contribution to the battle.