I tried this yesterday and my first attempt everything went well until a mob decided to shadow volley my healer at 150k health. I made it to 50k when the last guy died. After that attempt I would get owned well before 500k health. I tried positioning my guys all over and nothing helped. About 15yards away from the npc worked the best but eventually some adds would come and own my team. I tried by the door to HoR but I got owned because of all the damage. I ignored the brand but I think it was doing too much damage to the tank. My tank was nearly dead with full lifebloom, rejuv, regrowth and heals. At this point I think he is not doable with my team. If someone has a better tactic I would like to hear about it.