Solo'd this mob on my 26 feral druid. Root, then pop bear and charge, bash, maul, repeat...finished with almost 50% health.

I have figured out how to beat this mob!

get a 25 man heroic naxx geared raid cause you will need the gear bad! also make sure none of u have been slain by hogger that will instantly wipe the raid at phase 3

Phase 1: He will start casting Pyroblast on all of your dps. once he reaches 85% he will enter phase 2

Phase 2: He will cast Mind Control on the 5 people with the most threat. you must keep your healers safe. and this cannot be despelled. once you get him to 50% he will goto phase 3.

Phase 3: He enrages and gains Aura of Fail, this will instantly kill everyone in the raid if anyone has been slain by hogger. he also gains the same abilities as phase 1. get him down to 10% and he will reach phase 4.

Phase 4: at 10% the leader of the blood elves / leader of the draenei comes to aid you. like last phase, he gains the same abilities as phase 1. once he reaches 5% his damage is increased by 3000%. at this time, you must kill him as fast as possible.

Drops: the Ashbringer and 100,000 gold