The Forbidden Book is a document in The Amazing World of Gumball. It plays a crucial role in "The Mirror," where it reveals how to break the curse of the Snatcher, and contains useful spells, including one that allowed the group to advance the time to the following morning (albeit with a price).
This book also has a spell to give mortals the ability to touch ghosts, at the price of living a lonely existence inside mirrors.
- Tempus fugit ("time flies"): Moves the universe forward in time, at the cost of the incantor's youth.
- Beautio eterno ("eternal beauty"): Grants the target eternal beauty, at the cost of the incantor's life.
- Resurrectio mortis ("resurrection of the dead"): Resurrects the target from the dead, at the cost of the incantor's body.
- The book bears a resemblance to the Necronomicon Ex-Mortis from the Evil Dead franchise.