When you have done this fight enough times, it becomes a real joke and when I hear of raiding guilds on my server not being able to kill him still with the damage buff, there is something wrong. He was a pain in my side in 25 man for a while but now our ranged can kill the beasts with quick timing, giving us plenty of time to kill him. Last nights kill he cast 3 Marks, one fairly early on and we just let the person die and DPSed through it, the 2nd person had a DI put on them by me and I was the only paladin in the raid anyway (surprising since we usually have about 4 or 5), the 3rd was just healed through. The key element to the fight is killing the adds as fast as possible if you are ranged. Hunters can make use of distracting shot and multi-shot to bring the beasts away from the boss and then nuke them down. And yes, area of effect damage does not harm them that much, but it will pull aggro easily. When I DPS I don't cast Consecration for a 45 second period between the point when the beasts are about to spawn which is usually 8 seconds prior and then I wait until the ranged have them outside the radius of the spell before casting, same with Divine Storm.
does one suppose a warrior's piercing howl is useful in this enounter..especially in 10m hardmode etc