Quote Originally Posted by sync00 View Post
The slaves are naked and can't kill anything.

I clear from the start of the entrance to the gate where the rats attack you. Then I move the slaves about half way to the gate. There are no mobs in sight where I park them and I don't see how it could be too close to mobs.
I am assuming that they have not changed that mechanic in Stratholme. Periodically, a non-elite undead mob (looks like a black ghost) will spawn near the group and you'll see an emote or yell like "The Eye of Naxxramas says The living are here!"

If it is not killed within a few seconds, two elite gargoyles will spawn and attack the group. The ghosts do not spawn when the instance is generated, so it doesn't matter that you cleared every mob you saw.