Build used. (Obliterate sucks)
For what it's worth,
This isn't a fast run or speed clear by any means (which I tend to enjoy more). This was all of our first attempts at this instance, and it was just a pug. I went with a warlock buddy from Tich, Socio, and we just joined up with 3 random dudes.
You can see the disparity between tanking spell casting bosses and hard hitting bosses. The first boss was actually the toughest, mostly because he randomly shoots these chains at someone and stuns them for the duration. This makes the first boss fight much too reliant on having a resto druid healer (basically someone that can keep heals going while CCed). The chains effect is physical, so grounding totems don't work. It is rather funny to watch, though, since after I died, the other DK ressed me as a ghoul. I then ended up killing the boss like that. =]
The second boss was a pushover, as I could mitigate a ton of his damage.
I'm not really sure what the third boss did, but it didn't seem too bad.
The last boss lays out a lot of AOE magic damage, and randomly mind blasts/sleeps a target other than the tank. Acclimation is a huge boon here. In fact, I'm more inclined at this point to prefer acclimation over Anti-Magic Zone. As I've stated before in an earlier alpha synopsis, acclimation requires no runes, no global cooldowns, and is constantly being refreshed on you and your raid. It's fantastic, and it stacks with frost aura.