MAP11: Will you be my NME? (Plutonia Revisited)

Secrets

 * 1) In the southwest of the red skull key is a wooden cube with a chaingunner and a candle on it. Push it to open an alcove (sector 1148) in the wall north of it, containing two rocket boxes and a rocket launcher.
 * 2) The yellow skull key is placed in the middle one of nine recesses in a wall. Open the southernmost part (with the lantern) of this wall to reveal a switch. Pushing it opens a passage in the northernmost part of the wall. In there, you find two more rocket boxes and another rocket launcher (sector 1157).
 * 3) Using the red and yellow switches opens three sets of doors. Enter the one in the south of the switches where the arachnotrons came from, ascend the stairs in the northeast of this room, kill the mancubus and the revenant and walk behind the pillar where the imps came from. Push the recess in the green lights on the pillar's eastern side to open an alcove (sector 1165) with a soul sphere in it in the northeast of the room.