Accessed through a broom cupboard near the kitchens of the palace in Firetop, this long, winding stair leads straight down to Skullport. Although the fastest and most direct route there from the town, it is particularly prone to the shifting nature of Undermountain, and it is rare indeed to find the same connections and links along its length. It is also used by many of the foul creatures of the dungeons as an accessway between the Dungeon Level and the Sargauth level, although those access points are sporadic and unreliable. There are also often devious trapped rooms that appear along it. Those killed by the traps are seldom seen again, removed by whatever process it is that shifts the rooms along the stair periodically.
Entry can be gained by rubbing a human skull across the back wall of the broom cupboard, a process which uses the skull up. It is mostly used by Agents of the Eye to move between their base and Firetop. It takes about 12 hours of travel to descend the stair, and about 18 to climb it, which is usually more than a traveller can manage in one go.