As I said above, I run DK+4 Rets. I was able to get him down on normal mode which still really hard for me. The trick is that you need a mod to announce what's coming. The amount of damage a melee team takes is pretty high but there's not a whole lot you can do.

I think I can probably do him on Heroic right now but there's no real point. I'm going to farm the first two bosses in PoS on normal mode for emblems and the PoS trash for the Hilts. Since you can do all of the Hilt quests in normal mode...