As the PCs investigate the tunnels under the cemetery, they should encounter a solitary, silent, robed figure standing in the darkness. When it turns to look at them, they see that its face is a mass of wriggling, writhing earthworms. What the PCs have yet to discover is that a small group of Skwirm have set up an advance colony under the graveyard. They have been feeding on the corpses buried there while they establish a beachhead for a future invasion of the area.
Skwirm (3) (AL C, MV 120' (40'), (Dig 90', (30')), AC 6, HD 8, #AT 1 (weapon or constriction), per weapon or 1d6, SV L4, ML 9, mutations: metaconcert, hyperburroring, dermal poison slime, dual cerebellum)
The Skwirm will lash out with one of its worm tendrils at the intruders, hoping to ensnare and subdue the strongest-looking of the group while also doing 1d6 hit points of damage from constriction and 2d6 points of damage from its dermal contact poison. If combat starts to turn against it, it will silently "call" its two other Skwirm-brothers using its metaconcert ability. The other two Skwirm will come to its rescue, bursting out from opposite walls of the tunnel with their hyperburrowing mutation. One of them will be riding a Small Purple Worm (half the size of an adult Purple Worm) (MF rulebook, pg. 90).
Small Purple Worm (1) (AL N, MV 60' (20'), AC 6, HD 10, #AT 2 (bite/sting), 2d8/2d8/poison, SV L5, ML 10, mutations: gigantism, toxic weapon)
The Skwirm managed to get their "hands" on a newly hatched Purple Worm, raising it as their own. It will defend its "parents" to the death. Once the Skwirm and the Purple Worm are defeated, the tunnel complex can be searched. It's quite extensive, spreading throughout the area (and possibly leading to other subterranean adventures!). The PCs may also locate the Skwirm's hoard consisting of 835 gold pieces, two Satchel Charge As (4d6 points of damage, 10' radius), and a fully stocked survival kit.
Defeating the Skwirm's advance colony will set back their planned incursion of the area by several months. However, the Skrirm will then send a scouting party to the area to find out what happened to the original colony, starting the whole thing over again, as the Skwirm are tenacious and single-minded of purpose. The party may be called upon to find a more permanent solution.