I loved that one! My groups enjoy the workout. It's possibly my second favorite "omg I'm gonna die this time" mass of mobs, the first being the initial horde of zombies that spawns at the end of Skadi's hallway.

There's one like the Mystery of the Infinite in Tanaris, where you need to use the dowsing rod on the Sandsorrow pond. The sillithids that spawn are pretty beefy and I've wiped there, but I refuse -- yea, REFUSE -- to do it one at a time because the AOE gods are hungry and occasionally demand a sacrifice or five. It's a stupid principle but it's principled all right.