This level occupies the map slot MAP32. For other maps which occupy this slot, see Category:MAP32.
In the front of each skull key are triggers that release/let teleport monsters into areas that have been cleaned yet. The most switches have the same effect.
The blue switch just opens the blue bars. In the northeast of the blue bars is a room with a cyberdemon, and a zigzag stone walkway over a muddy ground. To its north there is a small room with a fake exit in it. As soon as the player enters this small room, the blue bars are lowered and cannot be opened anymore from the northern side. Thus, in singleplayer mode, the final battle area's monsters, released by walking into the fake exit itself, cannot be escaped from. (So in coop mode, the player with the blue skull key should stay in the southern part of the map, wait for the fake exit is activated, the room containing it is left by all players and then using the blue switch again.)
From the map start, walk to the south along the hallway. In the U-shaped room, enter the western door. Push the skull switch on the western side of the northern support beam. Return to the room north of the U-shaped room, where a niche (sector 6) in the northwestern corner has opened. Inside, there are one (on easy skill levels) or two (on medium and hard skills) barons of hell, one (easy) or three (medium and hard) bulk cells, and four medikits.
Return to the room where you pushed the skull switch in secret #1. This time, use the skull switch on the western side of the southern support beam to open an alcove (sector 236) in the north of the room you are in. Kill the (one on easy or two on medium and hard skills) barons of hell and find two bulk cells and a megasphere.
In Doomsday 1.14.5, the player spawns "as a camera" in this map, able to use all his (invisible) weapons, ignored by monsters, able to fly and move through walls, floors, ceilings and thus unable to play the map as intended for now. The line Player #0 spawned as a camera is found in the doomsday.out logfile. Workaround: After the map starts or a savegame in this map is loaded, enter the command makecam 0 into the console.