The Tome of Eternal Darkness is a fictional book featured in the video game series Eternal Darkness: Sanity's Requiem. This ancient tome contains knowledge about dark magic and the history of various civilizations, detailing their encounters with malevolent entities known as the Ancients. Players use the tome to uncover secrets and solve puzzles throughout the game. In the game, the tome serves as a central narrative device, guiding the protagonist, Alex Roivas, as she battles against the forces of darkness. The book's pages can be filled with spells and lore, enhancing gameplay and deepening the story's complexity. Its unique design and content contribute to the game's eerie atmosphere.