Dec 16th 2008 11:55AM No need to move at all on this fight if you have a good healer.
We always stack on the tank, and stay there throughout the fight.
The blast hits for 12-14k (on heroic), so of course your group will need to be geared well enough to not be one-shotted.
The healer (me in this case) just needs to keep everyone topped off and have a heal on the way so it hits right after the blast.
If you're with a group of new 80's, then yeah you'll probably want to work out all the movement, but if you're geared well, there's no need.