Update from last night:
Using the given tips, we did much better, but we unfortunately ran out of time before we got to a solid, working strategy. We managed to bug Grobthok out a bit, in that it seemed that having him underneath the magnet as he started to cast pipe smash would break his cast, and after the magnet broke, he would immediately cast pipe smash again. This caused us to take a little more time than we wanted to getting past him, despite one offing each of the two prior bosses.
In all, though, when not beset by what seemed to be bugginess on Corruptor, we managed to get him to the Unified Beam phase, in which we lost sight of him, and he wiped half the raid with the first blast, which was our last attempt.
This leaves me with a few questions:
1) Has anyone had trouble with Anti-gravity field where if you got out of the circle with less than, say, 0.5 seconds remaining on the cast, it rubber banded you back into the circle when he finishes the cast? It happened to quite a few people in the raid over our various attempts, though it was only fatal ~50% of the time.
2) When we got to the Unified Beam phase, a bunch of adds spawned immediately before he jumped, in the area where he landed, is there any way to avoid getting the adds to spawn then, so we can properly find him on the mini map? When he hit 40%, we initiated a hard burn, and tried to race him into that phase before another set of adds spawned, was that a bad idea?
Unfortunately, it seems as though we may not get to make more attempts at him this week, due to conflicting schedules on the team, but we can feel that we're getting close.
P.S. To those who suggested tank swapping as soon as the stacks fell off, that made us take a much more manageable amount of damage, and a tank died to too much damage only once, when the healers couldn't reach him after he got knocked away, thanks for the suggestion!
0. Yes, I've seen that "bug" too. I don't know if it's a bug, but basically don't tank him right under the magnet. Wait til he gets his pipe, then get to the magnet quick. I try to tank him in the middle of the room, close to the magnet as it moves around.
1. Ya... we have seen that too with anti-gravity, where you should jump as you are leaving the red circle. This has helped us... I'm not sure if the technology works so that jumping updates the server on where you are, or something, but we find that it really helps.
2. I thought he lifts up for Unified Beam at 25%... which means you have to make sure all major adds are dead before that.