Mission Found Argent Energy Tower
Access the Map
After activating the Argent Drones, exit the control room and head to 4-A on the opposite side of the tower. Wait for the Drone to exit its dock and hop on. Ride it all the way up and jump forward to find the lever. Pull it to open the Classic Map directly below. With the Drone away from its dock, enter the room to find ammo, health, and armor.
Map Strategy
Halls of the Damned requires three keys to complete: blue, red, and yellow. Start by collecting the blue key. Use the Berserk powerup near the outdoor switch and enter the new door on the left, next to the blue door. Fight your way to the left to find the first key. The other two keys can be picked up in either order. Fight your way through the darker tunnels and search the corners to find the red key. A few Pinkies inhabit this area, so try not to attract a crowd. Look for the gray, stone corridor and follow it into a star-shaped room. Enter the right door to find the last key. Watch out for Cacodemons. To exit, go through the blue door you passed earlier, followed by the red, and finally yellow.