SIGIL + Buckethead (v1.21) torrent

Sigil takes place after E4M8 and before Doom II. After killing the Spiderdemon, Doomguy steps into a teleporter. However, Baphomet glitched the teleporter with his hidden sigil, which brings Doomguy to dark shores of Hell. The Doomguy has to fight through this stygian pocket of evil to confront the ultimate harbingers of Satan, then finally return to become Earth's savior.[2]

Baphomet was only doing Satan's bidding by bringing you back to Hell. Somehow they didn't understand that you're the reason they failed in the first place.
After mopping up the place with your arsenal, you're ready to face the more advanced demons that were sent to Earth.
Lock and load. Rip and tear.