Invulnerable cage:
Last night I was in a level 8 fractal with Cliffside, and I was first put into the cage. Well, this cage was invulnerable (if you enter the room and look at the seal from the hallway, it’s the one on the right, placing it at the corner to the path to the next room on the side). No amount of damage would affect the cage, nor was it targetable.
Another person was put in the cage with me, and then a third. Three of us in this invulnerable cage and the other two members of our party inexplicably aggroed the room and were defeated.
Our thief (in the cage) could somehow shoot some of the nearby mobs with his bow (my skills could not penetrate, perhaps because it was a bouncing attack?), however they soon went invulnerable and we had no way to die, so it became an impasse.
Same thing happened to me, only 4 of my party members were in the cage :p
Have a look at the screen