Monastery Mayhem

[Thanael]

All of these tactics are designed to provide cover for the improved ghast necromancer, who has used magic jar to take over a living creature. As the living body is no longer subject to the holy protections of the monastery, the ghast infiltrates the complex in an attempt to find a way to bring down the ward and allow its horde to overrun it.

That is just awesome. He can even switch between several of the 24 npcs and simply hang around the PCs to see what they unearth or go along investigating himself. If his host dies in some trap he just switches to the next. The PCs have to find out what the hell is going on and who the saboteur among them is. Classic!