Curse of the Crimson Throne
Korvosa‘s Gray District is riddled with underground chambers, some of them burrowed by ghouls or other monsters, others remnants of ancient Shoanti burial grounds. Some of these warrens are patrolled and kept clear of monsters by the church of Pharasma, yet the Gray District is a large place and the tunnels below are vast and tangled. The Pharasmen focus on containing the problems with undead and necromancers, but as soon as they wipe out one, it seems as if two are ready to spring up in its place. The problem’s particularly vexing in Potter’s Ward, where the bodies of the poor and homeless are buried. According to Thousand Bones, the Dead Warrens were one of his people’s burial vaults, chambers that lie under Potter’s Ward.