With the latest DLC out for DOOM Eternal, there’s a lot more slaughtering to be done. With this Doom Eternal The Ancient Gods Part One Collectible Locations Guide, we’ll help you to find every secret there is on the map.
Doom Eternal Ancient Gods Part One Collectibles Locations
There are a number of collectibles and secrets to be found in the first mission.
Various of these will help you in getting up to speed with the lore of the game, while others offer a tough and varying challenge to the Doom Slayer.
UAC Atlantica Facility Collectibles
Codex Entry #1 – Book of the Seraphs Part 1
As you start off in the mission, you’ll find the first Codex Entry as you head into the facility and descend down the stairs past the locked door.
The entry is right by some boxes prior to the entrance of the next room.
Secret Encounter #1
Through the open area, head up into the elevator. You’ll be swarmed by a bunch of demons.
If you head back down to where you came from by jumping off from the railing, you’ll discover there’s a secret encounter that’s now spawned.
Codex Entry #2 – Book of the Seraphs Part 2
Head up the elevator again, and proceed further to find a switch. Hit it and head up the stairs next to you to find the second Codex Entry.
Codex Entry #3 – Book of the Seraphs Part 3
From the air vent that pushes you forward. Swing on the bar, and instead of attaching yourself on the wall, circumvent around it to climb the railing ahead of it.
You can find the third Codex Entry at the end.
Codex Entry #4 – Book of the Seraphs Part 4
When you enter another facility yet again, the Intern will contact you regarding the Seraphim’s key. From this point, head behind the stairs to find the Codex Entry.
Slayer Key and Slayer Gate
As you swing in the large empty gap, and with the drone attacking you, take a little detour and turn right to find a purple-glowing vent as it houses the secret Slayer Key.
To find out more about the Slayer Gate is, check out our in-depth guide regarding the Slayer Key and the Slayer Gate.
Head through the opened grates, and turn left. You’ll find the Slayer Gate on your first left through the hallway.
Secret Encounter #2
After using the touchpad, go through the first gate and instead of going through the second one, dive into the water to your right, and head through to the vent.
This is the second secret encounter found during this mission.
The Blood Swamps
Secret Rune
Starting off, the secret rune can be found under the main objective’s marker in the open area.
Head straight ahead, and go to the path to the right past the breathing fire. Defeat the Hell Knight, and keep going forward.
Below, you’ll find a breakable wall. Climb up, and traverse the terrain ahead of you to find a secret rune.
Codex Entry #5 – Book of the Seraphs Part 5
Make your way to the main objective yet again, and jump the gap above the place you recently spawned into.
Below, in the next area; you’ll find an armored Mancubus. Dive into the radiation-filled pond to find the codex entry.
Codex Entry #6 – Book of the Seraphs Part 6
As you find yourself in the open area in the next part of the mission. Head to the left, and jump up to the next platform.
Turn left, dash to the bar and climb up the wall. Keep following the linear path and to the left, you’ll find the codex entry.
Secret Encounter #1
The first Secret Encounter can be found in a similar fashion. Follow the same path you did for the sixth codex entry. Jump down the hole, instead of turning left this time.
Break through the cracked wall. Continue, and climb up the wall.
Punch the box down, and continue right down the stairwell, around the wall, up the booster, and finally to the secret encounter.
Codex Entry #7 – Book of the Seraphs Part 7
After your fight with Whiplash, dive into the radiation filled water, and continue to the next area after completing the first trial.
Fight off the small wave of demons which includes a Mancubus and a Hell Knight.
Jump across the gap and collect the codex entry, along with a helmet.
Secret Encounter #2
From the big locked door. Head left, past the main objective, and right through the gap. Platform your way up, and punch through the green crack in the wall.
Punch the box down, and push the skull in. Below, you’ll find the second secret encounter.
Codex Entry #8 – Book of the Seraphs Part 8
To the side of the castle, you’ll find platforms to take you to the main objective. Instead of going there, head to the climbable wall ahead of you first past the rotating bars.
Turn around, and dash to the final codex page for this mission.
The Holt Collectibles
The Slayer Key
The Key can be initially found as you jump onto the log and get to the top of the waterfall. Simply turn around, and platform your way back to find the Slayer Key to your left.
Secret Encounter #1
The first Secret Encounter for the mission can be found up the small waterfall. Turn to the right, as you enter the cave to spot it.
You’ll be pitted against a Mancubus and Spectre. Deal with both of them to complete the first Secret Encounter for this mission.
Secret Extra Life
From where you platformed on towards the Slayer Key. Turn in the opposite direction towards the main mission path, and look to the left to find a crack in the wall. Break it to find a secret extra life.
Slayer Gate
Head forward through the main path, and follow the path branching to the right. Defeat the Arachnotrons and you will find the Slayer Gate to the right.
Codex Entry #9 – Book of the Seraphs Part 9
Continue through the main path, and platform your way forward. Eventually, you’ll reach a point where you’ll have to jump across the void below you.
However, before proceeding forward, there’s a Codex Entry that lies underneath you on a small platform.
A notable landmark for this place would be the fallen tree above that’s making a bridge.
Codex Entry #10 – Book of the Seraphs Part 10
Deeper into the mission, you’ll reach the fortress eventually. To the right on a floating platform, you’ll be able to find a secret codex entry.
Secret Encounter #2
Prior to resurrecting the dark lord, head into the unlocked door to the right. You’ll find the encounter being blocked by red lasers. Activate the mechanism in between and shoot the target up top to access it.
Codex Entry #11 – Book of the Seraphs Part 11
After using the booster as you progress forward and using the bar to propel yourself onto the next platform, head to the path leading off to the right and into the door. To the left, you’ll find the 11th Codex Entry.
Codex Entry #12 – Book of the Seraphs Part 12
Continue through the main path, as you swing across and shoot the activation pad mid-air. Turn back, and shoot the pad yet again to unlock the door. Behind this lies our 12th Codex Entry.
Codex Entry #13 – Book of the Seraphs Part 13
Head through the same path and use the bar to swing across (Don’t forget to shoot the pad). You’ll find this Doom Eternal Ancient Gods Collectible to the right.
