MAP12: Altar Of Pain is the twelfth map of Doom 64 and has the secret exit to MAP30: The Lair. In order to find the secret exit you need to find a column with a soul sphere on it (the column is shaped like an arrow towards a wall). If you run into that wall you will end up in a cave with a Baron of Hell and the secret exit teleporter. The rest of the level consists of breaching a fort and fighting lots of demons along until you find the actual altar of pain and the exit.