my 5 box team has a druid in it for heals but my tanks sits at about 29k hp buffed and i'll say now that this is a very hard boss. between watching for who's getting pwned from above by the dragon, who's getting branded, and kiting the boss on unholy power through ice patches... it's a hell of a lot for one person to manage. even killing him in regular was very difficult, i have yet to get to him in heroic.