DOOM Eternal 100% Achievement Guide

Hello everyone.

Welcome to another of my 100% achievement guides.
As planned i will continue from the previous DOOM and do my best to help everyone out with achievements once again.
I will add new sections for DLC achievements as they release and keep you all updated in the comments.

Please feel free to offer feedback and comments good or bad so i can improve the guide, likes are much appreciated.

Thank you all!

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• This guide contains spoilers.
  
• In each category the achievements are in no specific order.
  
• Some achievements may be bugged which is out of my control, i will provide any useful info and updates if required. Comment section may also provide help.

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https://steamcommunity.com/sharedfiles/filedetails/?id=2036142586

Perform 33 Unique Glory Kills in a single save slot
You should naturally gain this achievement as you play through the campaign, if for some reason you don't then replay a mission or two and go glory kill crazy.


Upgrade Health, Armor, or Ammo
To upgrade each of these categories you will need Sentinel Crystals, you will gain your first sentinel crystal on Mission 1: Hell on Earth, then simply put your point/s into one of the three categories.


Complete Hell on Earth
This is part of the campaign and cannot be missed, you will gain this achievement when you complete the first mission Hell on Earth.


Complete a Slayer Gate
You will come across your first Slayer Gate on MIssion 2: Exultia, you will need to find the key to access the slayer gate which is usually hidden nearby.
Once you have the key you can enter and activate the hive which will take you to an arena for a big battle with demons.

There are 6 slayer gates in total and you will find them within the following missions:

• Exultia
  
• Cultist Base.
  
• Super Gore Nest.
  
• Arc Complex.
  
• Mars Core.
  
• Taras Nabad

Kill 666 Demons.
Simply kill 666 demons throughout the entire campaign, you should gain this naturally before you complete the campaign.


Kill the Doom Hunters
Kill all the Doom Hunters on Mission 4: Doom Hunter Base, there are 3 in total and you cannot miss these. You can use the plasma rifle to drop their shield and then lock on rocket launcher to finish them off.


Complete a Praetor Suit Perk category in a single save slot
For this achievement you will need to gain Praetor Suit Points to use in Perks, then use those points to fill one category. I started with environment at the top in purple.
To gain points you can complete mission challenges, find secrets/collectables and by using Sentinel Batteries in The Fortress of Doom.
Remember, you can replay a mission to continue progress towards any points.


Pick up 20 Extra Lives Total in a single save slot
You will find extra lives throughout the campaign, they are small green helmets with with 1up above them and are usually hidden as secrets, you should be able to gain more than 20 as you play through the campaign and explore a little, if not just replay any missions to gain any that you may have missed.
You can still lose lives no problem and any already collected will still count towards the overall number.


Spend 8 Sentinel Batteries in the Fortress of Doom in a single save slot
You can find Sentinel Batteries throughout the campaign and also gain them as challenge rewards. Once you have them you can head into The Fortress of Doom and insert them into the slots next to the locked rooms to open them, use 8 of them in your campaign to gain this achievement.


Blow a hole in Mars
This is part of the campaign and cannot be missed, you will gain this achievement on Mission 7: Mars Core.


Best the Gladiator in the Colosseum
This is part of the campaign and cannot be missed, you will need to kill the Gladiator boss on Mission 8: Sentinel Prime.


Fully upgrade Health, Armor, or Ammo in a single save slot
Each time you obtain a Sentinel Crystal put the points into Health, Armor and Ammo only, you will need a total of 12 but if you find all secrets etc you will max everything out anyway.


Acquire a new Crucible in Taras Nobad
This is part of the campaign and cannot be missed, you will acquire the Crucible at the end of Mission 9: Taras Nabad.


Kill the Khan Makyr
This is part of the campaign and cannot be missed, you will need to kill the Khan Maykr boss on Mission 12: Urdak.


Complete all Slayer Gates in a single save slot
There are 6 slayer gates in total throughout the campaign, you do not have to complete these during your first run, so feel free to finish the campaign and return to the slayer gates another time when you have upgraded and are stronger in battle.

You will find the slayer gates within the following missions:

• Exultia
  
• Cultist Base.
  
• Super Gore Nest.
  
• Arc Complex.
  
• Mars Core.
  
• Taras Nabad.

Complete the Campaign on any difficulty
As the title says, just finish the campaign.

Acquire the Unmakyr
For this you will first need to complete all 6 slayer gates, each gate complete will reward you with 1 of 6 keys.
Once you have all 6 keys take them to The Fortress of Doom and insert them into the device that holds the special weapon known as Demaykr, that will give you this achievement and the special weapon.


Kill the Icon of Sin
This is part of the campaign and cannot be missed, you will need to kill the final boss of the campaign on Mission 13: Final Sin.


Purchase all Praetor Suit Perks in a single save slot
To gain points complete Mission Challenges, find Secrets/Collectables and by using Sentinel Batteries in The Fortress of Doom to unlock them.
Just like the previous DOOM you will gain more than enough points for this by the time you finish the campaign but if you want to find all hidden items it's best to use a guide.


Beat all encounters and mission challenges, and find all Items in Taras Nabad in a single save slot
Taras Nabad is mission 9, you will need to find all the hidden items and clear up all encounters and challenges and then complete the mission. You can replay the mission and/or fast travel at the end to get everything that you need if anything was missed.
You can follow my guide below to find all the hidden items.

https://steamcommunity.com/sharedfiles/filedetails/?id=2036142586

Collect all physical Codex pages in a single save slot
As you play through the campaign you will come across Codex Pages that look like burning pieces of paper floating in the air, collect them all for this achievement, there should be a total of 54.
You can follow my guide below to find all the hidden items.

https://steamcommunity.com/sharedfiles/filedetails/?id=2036142586


Complete the cheat code collection in a single save slot
Find all the Floppy Disks located throughout the campaign.
You can follow my guide below to find all the hidden items.

https://steamcommunity.com/sharedfiles/filedetails/?id=2036142586


Complete the album collection in a single save slot
Find all the Vinyl Albums located throughout the campaign.
You can follow my guide below to find all the hidden items.

https://steamcommunity.com/sharedfiles/filedetails/?id=2036142586


Complete the toy collection in a single save slot
Find all the Doom Toys located throughout the campaign.
You can follow my guide below to find all the hidden items.

https://steamcommunity.com/sharedfiles/filedetails/?id=2036142586


Master all Weapon Mods in a single save slot
WARNING: This achievement is known to be buggy and might not pop for everyone, try and complete it without using the cheat codes (see comments).

Just like the previous DOOM you will need to fully upgrade each of the two mods for each weapon using weapon points, then complete each mod challenge to gain the mastery. Once you have completed all guns you will gain this achievement.


Complete a Mission with only the Famine Mode cheat on
First find the famine cheat code located on Mission 10: Nekravol
Then replay any mission with the famine cheat code activated. The first mission is the easiest and can be done in 15mins or less.


NOTE: You cannot replay missions in this mode to farm extra lives.

Complete Extra Life Mode with 10 Extra Lives in your Inventory
This is easy but time consuming. Start a new save and choose extra life mode, then choose the easiest difficulty unless you like a challenge.
As you play through the campaign pick up the 1up extra lives and you should end the game with more than enough.
If you follow a guide to find the locations of the 1up extra lives or you know the locations already then you should easily finish with over 30 lives left.

NOTE: You can track all progress in the milestones, just go to campaign>save slot>milestones>battlemode.


Play as 5 different Player Demons in BATTLEMODE
As the title says, play as each of the 5 demons in battlemode in no specific order. Win, lose or draw.


Do 5000 damage as a Player Demon in BATTLEMODE
Spend some time playing as a demon in battlemode and deal 5000 damage overall, this does not have to be in a single match, so have fun and this achievement will eventually pop.
Depending on your opponent and how good you are you can average at least 150-250 per match.


Play 25 BATTLEMODE matches
Straight forward to understand, play 25 matches in battlemode as the title says.


Kill 200 opponents in BATTLEMODE
This will take time to complete if you play naturally as demon and slayer, possibly 100+ matches depending how good you are.
The best way to do this is by creating a private match with three people total. Start the match and let one demon idle whilst you continuously kill the other demon.


Kill a Player Demon with each of the 8 Slayer weapons in BATTLEMODE
Use each of the weapons below to kill at least 1 player demon, this does not have to be in a single match.
It's best to lower their health first and then finish them off with the required gun, the most difficult is the BFG as you will need to choose it as an upgrade I think when it reaches 1-1 or 2-1.
If you don't want to do this online then create a private match for three of you and kill each other with the required weapons. Just note that a direct hit from the BFG does not count as a kill.

• Combat Shotgun - Use sticky bombs mod.
  
• Heavy Cannon
  
• Plasma Rifle
  
• Rocket Launcher - Use lock-on burst mod.
  
• Super Shotgun
  
• Ballista - Use arbalest mod.
  
• Chaingun
  
• BFG-9000

Heal yourself or your teammate for 50000 health in BATTLEMODE
You will need to do this as a demon only, use your demon ability to place a heal zone on the ground for you and your teammate to stand in and heal for 100 per second. It lasts about 8 seconds and you will need to wait for the cool down timer to use it again.

Complete the UAC Atlantica Facility
This is the first mission, complete it to gain this achievement.

Destroy the Life Sphere in the Blood Swamps
Complete Mission 2: The Blood Swamps to earn this achievement.

Defeat Samur in the Holt
You will earn this achievement when killing the final boss on Mission 3: The Holt.

Acquire all Support Runes in a single save slot
There is a support rune on each mission.

• Mission 1: Complete the slayer gate
  
• Mission 2: After killing the giant tentacle at the beginning, jump across and take a left and just past the flames is a wall you can break through that will take you to the rune. See my secrets guide if you get stuck with this.
  
• Mission 3: Complete the slayer gate

Complete all Secret Encounters in a single save slot
There are 2 on each mission, if you don't do them on your first playthrough you can replay the missions and complete these providing they are on the same save slot.

Collect all physical Codex pages in a single save slot
There are many to collect throughout the campaign DLC. You can find them all using my guide: https://steamcommunity.com/sharedfiles/filedetails/?id=2036142586

Complete Extra Life Mode with 5 Extra Lives in your Inventory
Start a new save on extra life mode and run through it on easy whilst collecting extra lives, you can use my locations guide above to find out where all the extra lives are located if you're not sure.

Complete World Spear
Easy, complete the World Spear mission.

Complete Reclaimed Earth
Another easy one, complete the Reclaimed Earth mission

Complete Immora
A third easy one, complete the Immora mission.

Acquire all Sentinel Hammer upgrades
These cannot be missed, you will need to complete the first phase of each escalation encounter. There is one on each mission except the final boss mission.

Kill the Dark Lord
This is the final boss fight, kill him for this achievement.

Boss fight guide:
You will need only the super shotgun for this fight.

• Phase 1
  1. Always stay opposite and away from the boss and use the zombies around the arena to stock up on health, armor and ammo.
  2. Do not attack the boss yet, wait for the dogs to come and kill them to charge your sentinel hammer.
  3. Once your hammer is fully charged, get close to the boss to trigger his attack and be ready to dash/dodge away. On one of his attacks he will turn green like the Marauder, at that point do not dash away and instead shoot him to daze him and then immediately use the sentinel hammer to extend the daze, this will give you enough time to shoot him 4 times.
  4. After the fourth hit be sure to dash away and stock up on everything again, then rinse and repeat the process. You will be using this same process through all five phases.
  
• Phase 2
  Same as above except he will dash at you before you can get close, so wait for him to dash and dash to the side twice to avoid being hit. Then get close and trigger his green attack etc.
  
• Phase 3
  Same as phase 2 but he will drop mines and you will have a Hell Knight chasing you, do not kill the Hell Knight and focus only the boss otherwise a big group of enemies will spawn. It's easy to stay alive even with the Hell Knight roaming around..
  
• Phase 4
  Same as phase 3 but will also spawn a big group of enemies as well as everything previous, kill the enemies and continue the usual process.
  
• Phase 5
  Same as phase 4 but adds another dash attack, you just need to keep an eye on the boss and be ready to dash away. The rest is the same process again.

Complete Extra Life Mode with 5 Extra Lives in your Inventory
Another easy run through extra life mode. Start a new save and choose extra life mode, then complete the mission whilst collecting extra lives along the way. You can find all extra life locations in my guide below: https://steamcommunity.com/sharedfiles/filedetails/?id=2036142586

Collect all physical Codex pages in a single save slot
If you need to you can use my guide below to find all codex pages: https://steamcommunity.com/sharedfiles/filedetails/?id=2036142586

Complete the first Horde Mode Mission
Straight forward, just beat the first Horde Mode mission.

• Cultist Base - Mission 1.

Re-collect all of the weapons on the Weapon Wheel
You will begin with the Chainsaw and a fully mastered Combat Shotgun. After each arena round you will be rewarded with another fully mastered gun at random, and at the start of certain arena rounds you will be given a special weapon. Get through all arenas to complete your weapon collection.

Beat Horde Mode
Complete all missions on Horde Mode to end this. There are 3 in total.

• Cultist Base - Mission 1
  
• Reclaimed Earth - Mission 2
  
• The Holt - Mission 3

That's it for this guide so far. I will be updating and cleaning it up where and when needed. For now, have fun and Rip n Tear!