Doom Eternal: Ancient Gods – All Codex, Rune Key & Secret Locations | UAC Atlantica Facility

The Ancient Gods expansion for Doom Eternal has arrived, adding three new lengthy levels to the main game. These levels are ridiculously difficult, pitting the Doomguy against the toughest demons in the game. You’ll be fighting pairs of Marauders in the very first level. You’ll be fighting Tyrants and Archviles without the Doom Slayer Sword.

These three levels have all the collectibles you’d expect from the main game, and earning them is especially important for two reasons. Finding all the Secret Encounters and completing them will get you a new Multiplayer Skin that you can access from the Customization menu. That’s three skins total for the first half of the DLC. Even better, finishing the Rune Gates will get brand new Support Rune powers, and a new slot to make your Doom Slayer even stronger.


More Ancient Gods DLC guides:

The Blood Swamps Collectibles Guide | The Holt Collectibles Guide | How To Unlock Support Runes & Which To Pick First


In the Ancient Gods campaign, you’ll earn new skins for completing all of the Secret Encounters in a stage. You’ll also earn new Support Runes by completing the challenging Rune Gates.

Codex #1: After gaining the Blue Keycard, go down the stairs near the upper door. If you enter through the lower Blue Keycard door, it’s straight ahead before going up the stairs.

Secret (1-Up): After the big fight in the large oil-rig room with fire-spurting and turrets, you’ll need to smash through a vent high above. Before dropping down, look for an optional path with a vent leading up. Jump up to find the 1-Up. This is in the vents above the red keycard room.

Secret Encounter #1: Take the elevator up after fighting the Marauder, then turn right and look for a wall you can climb before jumping after the Spider to the left. Down one floor from the ledge, there’s a secret encounter.

Codex #2: Jump the gap with Arachnotron and encounter the two turrets and Cyber-Mancubus. Behind those, there’s a switch you need to push. Go up the stairs to the left to find this codex on a raised ledge.

Secret (Full HP + Armor): Ride the cargo container on the crane to a circular arena. There a caged area to the left with the power-up inside.

Codex #3: Swinging and using the wind turbine to launch yourself to the scaffolding, look for a ledge to the right at the sealed door to the interior on the lower walkways.

Codex #4: After the encounter with the Doom Hunter, you’ll enter the main facility. It’s located behind the stairs.

The Slayer Gate and Key is down this hallway.

Slayer Gate: Past the point where the facility self-destructs, you’ll reach a combat encounter with a Tyrant. Continue into the hallway full of tentacles and ignore the main path to the left. Continue forward and the Slayer Gate is on the right.

Map: Continue past the Slayer Gate. You’ll encounter a Tyrant in a tiny room — defeat it and the map console is straight head.

Slayer Key: In the Map room, jump over the wall and look down — there are two poles you can swing on below. Swing on the poles and double-jump right to a vent.

Secret (+Armor): In the catwalk room with the three turbines past the tentacle hallway, go to the room to the left at the top of the stairs. Smash the vent at the end.

Secret Encounter #2: In the catwalk room with the three turbines that’s full of water, located right after the tentacle hallway, you’ll need to go to the office at the top. Press the button inside, the grab the environmental suit and swim to the bottom.

  • In the water, swim to the left to find a passage leading to the secret encounter.
  • You can also swim under the center turbine to find BFG ammo.

Secret (2-Up): This rare 2-Up is at the underwater base. When you have to fight the Tyrant, you’ll later dive back into the water. When you reach your destination you’ll see the 2-Up behind a locked door. Swim to the opposite end of the hallway and emerge to get it.


More DOOM Eternal guides:

10 Tips & Tricks To Start Demon Slaying Strong | Beginner’s Guide | How To Unlock The Unmaykr | Secret DOOM 64 Gun Guide | Cheat Codes Collectibles List & Locations Guide | How To Farm Weapon Mastery Challenges | Best Runes To Unlock & Equip First | Easter Eggs Guide | Tie-In Novel Trash, Dopefish, Unmaker & More | How To Unlock Doom & Doom 2 Classic