I recall just being flat-out unable to survive during this fight at level, although the details beyond that are a little hazier. So, I’m going to preemptively ask for advice while I eat my breakfast. Anyone care to oblige?
The problem my group had was people didn't understand the term "movement mode". You don't do it. If you do then the lightning balls come out and kill you.
Turn your movement mode off and don't stand beside the tentacles. Also probably best to leave the consoles to someone who has a shield, as tentacles will spawn beside the consoles.
No movement mode, rotate with the tentacles, watch the big ball he spits, stay max ranged, and let someone with a strong shield grab the terminals.
To add more specifics to "rotate with the tentacles," they first spawn on the right 1/3 of the room when facing the enemy as you enter the cavern. They will next move to the bottom 1/3 of the room, and then they reach the left 1/3 of the room. They move clockwise around the room throughout the fight, so the group has to move around the room to stay ahead of them.
My advice is that you read the following 3 times, and relate it to the folks you're playing with before the fight starts: Unsuccessful groups tend to scatter in this instance... and die. It helps immensely if a tank understands the general mechanic of the fight and leads the group around from console to console during those phases. Also no fast movement (as you get grounded anyway)
I do think a grounding mechanic should be added for the last boss like in COU. Getting people to not use movement mode is harder than herding cats.
