The south of the area, where you initially enter, appears to be empty of any foes except 2 to 3 stationary Skeletons of Dhuum, as well as one patrolling. However, there are 6 pop-up groups of Grasping Darknesses, and one Dying Nightmare. The group to the left of the bridge should never be popped in UWSC tactics, but each of the other groups spawns allied Tortured Spirits when killed. These allies will fight any enemies in aggro, and play a part in the Wrathful Spirits quest.
North of the monument is another patrolling skele, and several patrols of Coldfire Nights and Stalking Nights, as well as one group of Obsidian Behemoths. There is also another Dying Nightmare pop-up, which can spawn anywhere north-west of the monument.