but the last time I successfully killed him I had my shaman spread out in a diamond or square pattern in the center of the room opposite the golem, resto closest to the pally.
I tanked the golem in the narrow range between the two rooms ( dps at max range per say ).
in a perfect world you need to get the golem turned around to face AWAY from your team when he spits out the elemental ( this is harder than it sounds ) .
You HAVE to get the pally to hit the elemental ASAP with an avenging shield or at least a judgement before it has fully grown.

This seems to keep the elemental for the most part inbetween the two rooms.
for whatever reason he seemed to spit less at the shamans while so far away from the team... he also seems to enrage less.
move the team left or right once or twice and use healing stream totems x4.

Now the boss I can't finish is the last one in Gundrak.... I hate him with a passion. the stacking 5x dmg and stacking 5x reduced heals just vaporises my pally and if it doesn't vaporise him he looses aggro