You want to collect as much as you can in Doom: Eternal to unlock all of the secrets and find all of the hidden goodies developer id Software placed away. Many of them are on the map for you at every level, making them easy to pick out, even on the Fortress of Doom, your hub ship. An important secret many players will want to go out of their way to acquire is the empyrean keys. You use these keys to obtain the final, hidden weapon in the game.
To receive these empyrean keys, you need to complete the slayer gates found throughout the Doom: Eternal levels. Slayer gates are some of the toughest challenges in the game where players fight a powerful wave of demons, with a handful of mini-bosses thrown in there for good measure. You can complete these at any difficulty, and it will count toward unlocking the weapon. There are six of them available for you to locate in the game. They are on these levels:
- Cultist Base
- Super Gore Nest
- Arc Complex
- Mars Core
- Taras Nabad
You can finish them on your first playthrough of the game, or you can choose to repeat the game to go after them. If you’re revisiting the missions through Mission Select, you need to make sure you do not have cheat codes activated. Cheat codes are one of the secrets you can acquire in the game, and you can turn them on when repeating a mission through Mission Select. However, you won’t be able to access the slayer gate when secret codes are turned on. Developer id Software wanted to ensure players completed these naturally, without the assistance of cheat codes that provided infinite ammunition or lives.
For those looking for the empyrean keys, double-check any of the above missions to see which of the slayer gates you have not completed. Once you have all of the empyrean keys, you can take them to the Fortress of Doom to unlock the weapon.