Tanks: Feral Druid and Prot Warrior
DPS: Demo Warlock, Fire Mage, Frost DK, Somekindof Rogue
Healers: Holy Paladin, Holy Paladin, Resto Shaman, DISC PRIEST
So, anyway, we started the fight by releasing Storm Rider, Nether Scion, and Whelps. We had our rogue and DK focus-target interrupting the shadow nova (and since DKs currently have hit chance problems with their interrupt, our druid tank also helped on those ones).
We AOE'd down the whelps while single-target focused on Nether Scion (it seemed to do more melee damage). As soon as the whelps were dead or near-dead, I'd release the Time Warden.
As far as I'm aware, we had two drakes on our warrior at the start and Halfus on the druid. When the druid got too high on MS stacks, we used hand of protection on him (he had a macro to cancel it). When his stacks got to about 6, the other tank taunted Halfus. We had a second hand of protection prepared for that tank, as well. There was some drake swapping, I'm sure, and the druid always picked up Time Warden when it was released. I'm not really sure who had drakes aside from what I've already said. I don't think the Halfus tank ever had more than one drake, though, for obvious reasons.
And that was it... adding the disc priest made everything much, much easier. We never touched the Slate Drake and we beat the enrage by about 20 seconds.
Stupid fight is stupid, but at least it's more manageable when you bring a disc priest and 3 other healers.