Got Magmar down on Sunday night, which is actually quite an easy fight to do.
Big lava worm, who does lots of aoe damage and then does a pillar of fire so everyone has to run away from it, and after the pillar all these worms come out which have to be dps'd down before they get to the raid. Wash rinse repeat, until Magmar bites the tank and holds the tank in his mouth and then 3 dps jump on Magmar's head and chain it to the ground and then everyone can do free dps to the head for a while. Then Magmar breaks free and we start all over again.
So for a 25 man raid I put the pallies on the MT with one of the shamans and everyone is on raid. I tree form after the first pillar and then when the tank's in the mouth I get the shamans to mana tide for the healers and dps. Then when the CD is up again we do it again (at a later repeat of that cycle).
Pallies and priests are the big healers for the raids. I find I am only just ahead of the shamans for healing on the charts.