Caves of Erythnul

Unlike the other wings of the Black Cathedral, the caves of Erythnul are little more than natural fissures within the rock. The grimlocks who dwell here arrived several months ago at the behest of their leader Grallak Kur, a cleric who led his followers on an unholy pilgrimage through the Underdark. Dreams and visions sent by one of Erythnul's minions guided Grallak's steps until he arrived here. While the other factions distrust the grimlocks, they provide a convenient buffer between the forces of Hextor and Vecna.
The grimlocks lack both the time and the inclination to sculpt their environment. They dwell within the caves here, a series of winding passages punctuated by a large, U-shaped cavern. Travel through this area is difficult, as the party must contend with rough ground and sheer slopes. The grimlocks, accustomed to difficult travel through perilous terrain. navigate the caves with ease.
The caves are lightless, and the walls are rough and cracked, making them relatively easy to scale. Unless otherwise noted, the cave floors are difficult terrain. They are pitted with shallow holes, rocks, and other debris that make travel difficult.