Part 20

Locate Rune Challenge 8.1 (SECRET 8.8) by looking out over the chasm and turning 90 degrees left to find an airlock leading to the Rune Trial "Blood Fueled". A suit of armor is also nearby.

Find SECRET 8.10, a Classic Doom Level. Jump to the immediate platform, turn left, and drop to the platform below the Gas can. Turn around and jump to the platform indicated by a green light-bar. Continue around the rock, jumping up to the top where a suit of armor is located. From this top platform, face opposite the entrance area and jump towards the pipes and lever. An invisible ledge exists about 12 feet below the lever; the In-Flight Mobility Rune (especially upgraded) can help reach the lever from this position. Alternatively, access the switch from the platform near the Mega Health Powerup.

From the lever, face the piping, jump onto it, duck, and turn into the cave to find SECRET 8.6, COLLECTIBLE 8.1, "Supershotgun Model / Phobosguy".

Return to the high point where the suit of armor was. Look for a lower pinnacle and jump there. Turn about 45 degrees right to find the Mega Health Powerup, SECRET 8.5. A Cacodaemon will appear after collecting it.

From where the Cacodaemon appeared, locate a bay opening containing ARGENT CELL 8.1, SECRET 8.4.

Find a hatch that opens and closes (the in-game waypoint (a marker on your map you've manually placed as a destination) should guide you). Jump onto it for an irreversible Checkpoint (an auto-save point you restart from on death).

In Mission 8: Twin Intake Area, find a Field Drone behind a grate between the twin intakes, accessible from the other side. Jump onto a rectangular panel, then onto a walkway, and then to a green-lit hatch to reach the top of the air intake.

Proceed through the tunnel where an Imp will appear.

Reach the other intake, turn it off using the panel, and jump down the hatch into a shaft containing FIELD DRONE 8.1.

Reverse your steps, turn the air intake back on, and ride it up.

At the 4-way shaft intersection, proceed toward the in-game waypoint leading to BFG Labs Lobby. Armor is available in the opposite direction.

In the lobby, choose the large green door with the waypoint or the smaller door to the left housing SECRET 8.3: ELITE GUARD 8.3.

In Mission 8: Fight: The BFG Labs Access Hallway, enter the ring of labs and defeat 5 Possessed Soldiers, 2 Possessed Securities, and 1 Cyber-Mancubus. A super-shotgun, rockets, and gauss cannon are recommended.

In Mission 8: Notes on the BFG Labs, explore the labs clockwise starting from the Yellow Door. Find a Torso in the Yellow Door area whose retina grants BFG access. In "Prototype Lab 02" (Bluish Door), fight 4 Possesseds. Near a Red-lit Door-ish area, find a corpse, Gauss Cannon, and plasma fuel. In "Prototype Lab 01" (Bluish Door), defeat 4 Possesseds, stand on machinery, and look for an open duct to find SECRET 8.2, COLLECTIBLE 8.2: "Pinky Model: Pinkguy". Follow the duct to a room with a Possessed and CODEX ENTRY "Weapons / BFG-9000".

Proceed to the in-game waypoint and interact with it to access the BFG.

In Mission 8: Accessing the BFG (Defeating the Security Measure), enter the chamber. Jump onto metal platforms on the walls and observe the security apparatus. After about 10 seconds, shoot 4 of the 6 visible cells when the lamps light up. The security system will collapse, allowing you to claim the BFG. Watch the cut-scene.

In Mission 8: Fight: Test The BFG, use the BFG or focus on Weapon Upgrades like the Super Shotgun, Gauss Cannon-Siege Mode, or Chain Gun-Mobile Turret.

Before proceeding, go through a newly green-lit door and turn left into a yellow-gold-lit opening to find SECRET 8.9, RUNE CHALLENGE 8.2 "Intimacy is Best".

Proceed into Mission 8: Gore Nest 2.