This map is generally safe, but provides surprises through ambushes. In addition, it's not significantly easier on the lower difficulty levels.
For those playing deathmatch on this level, you will only have access to the central area of the map, as one of the respawn points is rigged to seal off the northern and southern sections.
Entrance[edit]
When you enter, you should see a building to your right, with the entrance visible through the window. The first weapon can be collected from the former sergeant near the entrance, along with a box of shells. You can also get a double-barrel shotgun as well.
The first ambush is sprung when you approach the western edge of the interior room. Various lesser demons will shoot at you from the southern platform, and a hell knight is released from the eastern alcove. Deal with them, or flip the switch on the left and run through the door. Lower the lift to continue and kill the chaingunner on the lift.
To the north is the red key door, which you can't use yet. There is also blue armor, but collecting it may release monsters on the western wall, and also releases a mancubus in the south-east corner of the map. Flip the switch to raise stairs to the northern section.
Northern section[edit]
You need to collect the yellow key first, and it is located on the northern-most part of the map. After going up the stairs, follow the right corridor until you reach a red-colored barrier, then turn right.
The next room has two Arachnotrons next to the plasma gun, and two revenants waiting to ambush you as soon as you enter the room. There are also two pain elementals on the sides of the room.
To reach the yellow key, you need to enter the two sides. Entering a side raises a switch, which must be used to raise the platform to the yellow key. When both switches are ready, get the key. Once you do, monsters will begin to teleport into the center of that room, including a Baron of Hell.
Note that entering the northern area will release four chaingunners at the entrance.
Red key[edit]
The final section is in the center of the map. When you enter the room itself, two Mancubi and eight sergeants will appear in the room. Get the red keycard at the southern end of the room simply by touching the pillar.
With the red keycard, return to the entrance, and deal with the four chaingunners. Head to the red key door, open it, and pass through - this lowers the red barriers between the left and right parts of the map.
The exit is located to your left, once you pass through the red key door.
Secrets[edit]
There are five secret sectors, all of which are in one area of the map. When you first lower the lift leading to the blue armor and red key door, open the secret door to the left. This is a small corridor that leads to a backpack.
For the last secret, open the door behind the backpack, and enter it.