The Cult of Orcus
There are a few pockets of Orcus worship located throughout the Nentir Vale. Their cells are very difficult to weed out, but occasionally they rise from hiding to perform the bidding of Orcus.
One such cult headed by a scion of Orcus, known as Kalarel, had a small yet powerful following. They had located an ancient text pointing them to a “soft spot” between the world and the Shadowfell. The whereabouts was within the catacombs of the old Keep north of Winterhaven. Their plan was to open a rift to the Shadowfell so that Orcus could send a legion of undead through to challenge Winterhaven and the rest of the Vale.
Another pocket was found at The Wall. A cell grew there and made secret alliances with the orc tribes of The North. They had learned of a powerful exarch of Orcus, known as Azghul, imprisoned beneath The Ruins of Karnholdt. Led by Solomon the Traitor, they split off from The Black Cloaks to seek out the ritual that would undue the prison.
Both of these cells were vanquished by the adventurers.
A third group, much larger than a cell, has popped up in the underdark. A group of Orcus-worshipping drow have raided the dark elf city of Phaervorul and plan to raise an army of the dead to threaten both the surface world and the underdark alike