In DOOM: The Dark Ages Chapter 12, you can do the Skeleton Key Challenge and be rewarded with extra Gold. The challenge involves finding and opening two secret doors using a purple Secret Key. The doors cannot be opened with regular keys. Upon opening both of them, you’ll complete the challenge and be rewarded with 50 Gold. This guide will help you find the Secret Key and show where to use it.
Skeleton Key Challenge in Chapter 12
In order to finish this challenge, you must locate and open 2 doors that use the purple Secret Key. These doors will not open with standard keys. After opening two of these doors, you will receive 50 Gold as a reward and finish the Skeleton Key challenge.
Secret Key Location



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Go out from the ventilation shaft and kill all the demons in front of you to obtain the Secret Purple Key. Since the level is open-world, you can unlock the Secret Key Door in any order you like.
1. Secret Key Door



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Go down the elevator shaft and pick up the next Shield Rune. Finish the last red fight encounter, then go back to the side room with the Secret Key gate. Enter it to get the Kreed Maykr toy. Toys are hidden objects that are miniature, cartoonish figurines that each symbolize a different kind of demon that the player encounters during the campaign.
2. Secret Key Door



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Get your Wraithstone by eliminating the Agaddon Hunter inside the secret area. You can use the Secret Key to open a gate on your right to enter the secret section as soon as you exit the room with it. Since you need wraithstones to fully upgrade your weapons in Doom the Dark Ages, they are crucial items to collect.