Hey, I searched Heigan and found a similar post but this way is different and much easier, it allows you to get a garunteed "safety dance" acheivement on either 10 or 25 man and the only person that needs to dance is the tank.
There is a small ledge on the left hand side as you enter Heigan's room at the top of the dirt pile, you need to stack the raid up on there. (NOTE: If your melee are competant enough, have them do the dance, but for a garunteed achievement just have them stand uselessly with the casters on the ledge.)
The tank can then tank Heigan on his platform ensuring that he is in range of healers and the boss is in range of dps, this is easiest if the tank stands on the small slope leading up to the platform with the boss on the flat part, this way he will not need to move the boss in phase one.
Phase two involves the tank and any melee you deem competant enough doing the dance while the casters continue to dps the boss as he should still be in range while in the centre of his platform. Rinse and repeat.
Note: If you fall off the ledge it is impossible to get back on unless you are a warlock with a teleport there, this is because you need to run along the wall and the door prevents this when it closes. So be careful since falling off halfway through the fight will almost certainly kill you,
Screenshot of the caster group:
http://i82.photobucket.com/albums/j2...230/heigan.jpg