Necronomicon

A book that can be bought from Pocketcat, after trading him in one child, either the Little Girl or the Demon Child.

Uses
Can only be read once and the player learns either one of these skills: Necromancy, Blood Golem, and Blood Portal. However, it comes with a cost: a coin flip. 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 the three blood 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.