Went in blind on hard. Got bonus boss on second try. CC two adds, dps one at a time.

Guardian tank (me)

Sage healer

Vanguard dps

Scoundrel dps

Fighting the special trash mobs was pretty fun and yeah the L4D references were not missed by us either. We mostly breezed through it. So much so that we actually left at one point to make sure it was hardmode.

To above, no we did not kill all 3 adds before the boss "woke up". I just had to tank them both with careful use of cooldowns. It is a lot of damage though.

Anybody got any tips for a heavy melee group?

Our group was:

 

Vanguard tank

Scoundrel healer

Shadow dps

Guardian dps (me)

 

We pretty much breezed through the non-bonus bosses (hardmode), but we couldn't even get past the first add phase of the bonus boss. Are you supposed to be able to burst down the 3 droids before he is done with his shield? We usually got 1 down with 1 cc'd and a third one with about 20% hp left, but the boss got back before we could kill all 3. 1 of them alive, plus the boss is just too much of a strain for our healer.

It is a very heal intensive fight, aoe healing is very good here.

If you have problem with the adds, then, CC 2 of them, kill the 3rd, and then kill them 1 by 1, the boss does not seem to have an enrage timer, so as long as you kill the 3 adds and dps him a bit, you should be fine.