After another 8 waves of trash, Anetheron comes charging in. At the start the MT will again pick him up and pull him roughly to the center of the arena like previous with Winterchill. During the positioning of Anetheron everyone should loosely spread out to avoid AoE abilities. The OT will tank the Towering Infernal near the tower.
The biggest ability here will be the Vampiric Aura. From the start and the rest of this fight Hunters should use Aimed Shot, Rogues use Wound Poison, and Warriors use Mortal Strike if they are specced. These debuffs must be maintained on the boss at all times!
Another equally dangerous ability will be Inferno. He will select a Lucky Winner and cast this ability on them. As the Inferno hits the ground it will damage everyone in an 8 yard radius and stun them for 2 seconds. This is part of the reason we spread out. At this point it is the Lucky Winners responsibility to run the Towering Infernal to the OT. They are immune to Taunt so wait with the OT long enough for him to take threat before you run back to your position. Hunter's can help by misdirecting the infernal to the OT. At this point, due to the AoE from the Infernal, the Ranged must focus the Infernal until it dies.
Carrion Swarm is the next reason we spread out. The ability itself is not anything crazy unless it hits a Tank. It will reduce healing by 75% and can be quite annoying for your healers. Stay spread to reduce the headache of this ability. Lastly we have Sleep. Blizzard put this here to annoy you pumpers. There is nothing you can do but eat the sleep. It can be problematic if RNG takes 3 healers or OT during an Inferno. I am assuming it ignores the MT.