Necronomicon

A book that can be bought from Pocketcat, after trading him in one child, either the Little Girl or the Demon Child. Can be found as random loot from a bookshelf.

Uses
Listed in-game as "Ancient book", it can only be read once and the player learns either one of these skills: Necromancy, Blood Golem, Hurting, Black orb, and Blood Portal. However, it comes with a cost: a coin flip. Unlike other coin flips, lucky coins cannot be used- only one coin will be flipped. Failing in the coin flip will cause the player to die from the madness of peering into the pages of the Necronomicon. Succeeding will make the player learn one of these five spells.

Trivia

 * The Necronomicon is a direct reference to the book, Necronomicon, that appears in stories of the creator of Lovecraftian Horror, H.P. Lovecraft, and his followers. It became so infamous that it was thought of to be a real and actual book at first. Since then, many have published books under the title, Necronomicon, after the horror author's death.