PEAK added a new Mystical Item in the ROOTS update, and this item can be used for rather dangerous, but rewarding properties. It's a double-edged sword to use the Book of Bones, and we've experimented with it to figure out exactly what the Book of Bones does, and how it can be used to get the Applied Esoterica Badge for your achievements sash, and cosmetics. Without further ado, check out the guide below so you know where to get the Book of Bones, what the Book of Bones actually does, and how it's used to get the Applied Esoterica Badge in PEAK.
What Does the Book of Bones Do in PEAK?
How to Get the Book of Bones
The Book of Bones is a Mystical Item that can only be acquired through a random chance by opening Ancient Luggage or Ancient Statues, but Ancient Statues only reward a Mystical Item if all players are currently alive. If players are lucky enough to get the Book of Bones, they will find themselves with a single-use item. The Book of Bones has two unique abilities:
- Revive players, but turns them into skeletons
- Turns the reader into a skeleton if no players need reviving
If you are looking at another player's skeleton on the floor, you can hold the interact button on the Book of Bones to resurrect them, but they will be revived as a skeleton. You can also turn yourself into a skeleton by reading from the Book of Bones without reviving a player, but becoming a skeleton has an unusual effect.
Once you become a skeleton from the Book of Bones, you will no longer be affected by Hunger, Burn, Frost, Poison, Sleepiness, and Spores. However, you will take over double Damage from falls and explosions, so be mindful, and your stamina will drain as normal, and items weigh the same. This can be extremely useful as a last resort, as you can use this item to avoid starving to death, or by skipping lava sections in CALDERA. However, the extra damage dealt makes you very fragile, and things like Dynamite are very likely to kill you instantly, but you can still use Medkits and Bandages!
How to Get the Applied Esoterica Badge in PEAK
In order to get the Applied Esoterica Badge, you will need to be playing in co-op. With the Book of Bones acquired from Ancient Luggage or Ancient Statues (at random), you will then need your friend to die. Once the friend you are playing with has died and has become a skeleton, you can look at them with the Book of Bones, which will see a prompt to revive them appear on your screen that says "[Player]'s Skeleton. (E) Revive?" By holding E, or whatever interact button you have bound to your keyboard or controller, you will use the Book of Bones to revive them. Reviving a player through the Book of Bones grants the Applied Esoterica Badge, which rewards the Skeleton Top cosmetic.
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OpenCritic Reviews
- Top Critic Avg: 83 /100 Critics Rec: 100%
- Released
- June 16, 2025
- Developer(s)
- Landcrab
- Publisher(s)
- Aggro Crab, Landfall





- Genre(s)
- Adventure, Exploration, First-Person