We started working on the fight last night (25m so adds are beefy) and we had a lot of trouble initially managing the rages. We are trying to burn them in groups of 8, so every other round. But we only have 1 DK, so we do not have enough AOE grips to keep everything stacked together. We initially tried to CC the Rages with AOE's like RoF x2 etc., but this doesn't last long enough and the Rages would get too close to us by the time they got caught in another one. With any of the 8 or 10 yard CC we found sometimes a Rage would just bypass it completely.
So we started to single target CC x 4 for the first pack, and then use our DK to grip after the second pack spawns and we've broken CC.
This was working but it seemed VERY cumbersome and we lose a lot of DPS time. Melee are on other duties so, aside from the DK, it is primarily ranged that have to burn down the Rages. If they don't all die in the exact same place at the same time, we'd have trouble with our Hunters being able to detonate them all before their deterrence expired.
First I just want to vent a bit - I think it is a little unfortunate when a fight can be completely trivialized by one class mechanic that is not distributed to any other classes. To a lesser extent I feel like Blizzard abused mass dispel too much in their design of this tier, but DKs vs. Will really takes the cake.
With that said, do you guys have some suggestions for a better way we might deal with this problem?
Also, what's a good guideline for minimum HP % on the Boss for each intermission? We were aiming for around 30% each and then burning bosses after the third intermission.