Originally Posted by
Zeuq
When my 10-man was working on that achievement, we tried zerging a few times, and all it takes is a small mistake and you often can't stop DPS in time (we'd often fail around 1-2% and DoTs would kill her), and you have to wait another week. Yes, it's doable with decent gear and a decent raid composition, but it really is a lot easier to do it the way it's intended.
The thing is, no one but the tanks should ever get close to failing. If they are, they're either taking unnecessary risk for a little extra DPS or they don't know how to LOS. The only hard part about the achievement is the tank time, which isn't bad with good tomb placement and prompt taunts. If they still have problems, just bring a third in to speed up the rotation, and thus increase margin for error, or try the pet tank method, and you should be able to get it within a few tries.
Honestly, once we stopped trying to zerg it in 10-man, we got it in three tries. Even funnier, just a week or so later, we did it on our first attempt in 25-man, and half the raid hadn't even tried it in 10-man. It really just depends on competent tanks.