Probably the most BUGGED instance of all time. Once you enter this dungeon you constantly get toggled in and out of combat the entire run, it never ends. There is also a problem with phasing, group members at some certain point becomes invisible and all you see is chevron plates floating.
The worst offender in this entire instance is Roost Mother. At some point (percentage) she will turn completely invisible / untargetable and the ONLY way to kill her is with sorcerer pets. It get's even worse after a wipe, she then turns invisible within seconds after initiating combat.
This is totally unacceptable and I don't understand why these issues haven't been fixed yet after 4 months. Maybe people really don't like grouping in ESO and in effect, no one has reported these bugs...