Part 9

Navigate the Foundry: Follow green lights to jump between platforms. Enter SECRET 3.1 (a square opening) for a suit of armor. Jump to the platform with a corpse, grab the biometric ID (arm). Jump back across the gap, defeating an Imp.

Gore's Nest 1: Head to the control console, use the arm, and turn to find the Gore's Nest. This fight involves ~5 Imps and ~3 Hell Razers.

Gore Nest 2: Locate this nest in the Foundry's Main Area. Prepare for a mix of The Possessed, Possessed Soldiers, and Imps. Use the heat blast or chainsaw if low on ammo. Destroy the Gore Nest.

Explore Tunnels Above Gore Nest 2: Enter the tunnels after clearing Gore Nest 2. This area is for exploration, with minor demons. Find CODEX ENTRY "Monsters / Imp" in a dead-end room with armor. Locate SECRET 3.4 by looking for a room with a rotating-red ceiling-mounted light labeled "UAC-HAL"; the ledge is to the right and slightly higher. Enter to find the secret area and the ROCKET LAUNCHER.

Middle Entrance: From the tunnel, find an observation room; the door is outside the window.

Upper Entrance / Yellow Keycard Guy Access: From the Yellow Keycard Guy, go down a staircase, turn into a small door. From the tunnel, find a green-lit room with white boxes; stand on them and jump to a yellow patterned ledge.

Obtain the Yellow Keycard: Exit the Field Drone area, go around the Blue Keycard Area. Fight 4 Imps, a Possessed Security, and two Possessed Soldiers. The Shielded guy is tough; consider the chainsaw. Taking the Keycard creates a CHECKPOINT.

Escape with the Yellow Keycard: Exiting the area triggers an ambush: 2 Imps, a Hell Knight, and 2 Possessed Securities. Run to the Field Drone location, lobbing grenades. The Hell Knight is the main threat.

Find Argent Cell 3.1: Use the Yellow Keycard to access a hot foundry area. Fight a mix of demons, using barrels for area damage. ARGENT CELL 3.1 is in the corner near a defunct door.

Discover Classic Map 3.1: From the yellow keycard area, look back at the walkway. Find a Lever on the right side of a crate. This opens a door in the fight area leading to CLASSIC MAP 3.1 "Doom - Nuclear Plant".

Use the Yellow Keycard: Before approaching the yellow keycard door, stock up on supplies. A Hell Knight will ambush you. Entering the door creates a CHECKPOINT.

Hall after Yellow Keycard: Enter the hall, dealing with two initial Possessed Soldiers. Then, a Hell Knight, Imps, and Hell Razers will spawn. Use grenades on barrels.

Find Secrets in the Hall: SECRET 3.5, COLLECTIBLE 3.1, "Plasma Rifle Model, Prototypeguy" is found inside a crate being worked on by robots. SECRET 3.2, ELITE GUARD 3.2, is found by climbing crates at the back of the room where a chainsaw rests.