You know what the real problem with the lowest level of the crypts is? It isn't the spawn, it's the locations that the knights come from. The majority of the skeletons come from the main room, so the tank tends to take up a defensive position there. But then other skeletons spawn in two or three locations behind the tank and that means that everyone in the group tends to get slaughtered, because the tank can't leave his spot at the doorway. And it's not as simple as putting a tank in the back, because the ones from behind pop up simultaneously, which means you need two or three tanky people in the back. And that's not generally viable for newbies.