Basically, the mission involved you being followed by about a dozen NPC buddies through a series of events. This lead into the “ossuary”, a vertical element with a spiral ramp, then some encounters at the bottom. Now, when you do this mission right (as I did. . . the second time through), you spiral down the stairs, fighting the enemies as they come and into the basement, which was faceroll easy. No threat at all. If you do it wrong, on the other hand, such as not paying attention and falling through a hole in the floor and dying in the basement, things do not go well.
Ok, my fault, I died, I respawned, I’ll pay the repair bill, but that wasn’t the bad part. The bad part was that when I fell to my death, the rest of the team went in after me. By the time I got back, they were all dead or inevitably dying on the bottom tier, with two giant veteran monsters and a dozen or so regular tier ones. I could not even pick at the edges and work my way carefully in, as I would in an open world encounter, because the enemies respawned far too fast, and were too closely packed for that sort of thing.
At this point I had no choice but to restart the mission, redoing about fifteen minutes or more of content prior to this point, which was hardly the worst punishment a game’s ever given, but was still frustrating. The second time through I avoided falling to my death and the rest of the mission was almost effortless.