With this item equipped in the Action slot, it enables the user to cast spells. The player's hand emits colorful sparkles in the loadout view, and the player can pick up and cast magic spells. When a player joins a server hosting a Halloween map that has magic spells without a spellbook equipped, a notification is displayed, allowing the player to equip it or decline the notice by the using the keys given in the notification (default keys: for accepting and for declining). The notification reappears after respawning until a spellbook is equipped, the server changes to a map without spells, or the player leaves the server.
Despite only requiring three Spellbook Pages to begin functioning as a Spellbook, players may continue to insert more pages into the book, which increases one of the counters in the description for the respective page type added. With the single exception of unlocking the Page of Tumidum by completing the "Helltower: The Mann-tastic Four" achievement, assignment of an inserted page to the other four page types, Audere, Congeriae, Gratanter, or Veteris, is random. Viewable by others in a public inventory, these page counters indicate the owner's level of activity in the Halloween Holidays. Other than this cosmetic effect in the player's inventory, the type and number of Spellbook Pages added to Fancy Spellbook have no influence on gameplay.
- The Fancy Spellbook was added to the game.
- The names of the page types in this item's inventory view are in Latin. They translate to the following:
- Tumidum: Swollen or distended; self-confident or presumptuous. A neuter adjective (tumidus, a, um).
- Gratanter: Gratefully or gladly; pleasantly. An adverb (= grate).
- Audere: To have a mind (to do something); to dare. An infinitive verb (audeo, ausus sum, ere).
- Congeriae: Not an actual Latin word, but is reminiscent of Congeries: A heap; collection or accumulation. A noun (congeries, ei).
- Veteris: A form of Vetus, meaning old, ancient, of times past. Another adjective (vetus, veteris).
- The publicity blurb is in direct reference to The Evil Dead, a series of horror films revolving around the Necronomicon, a spellbook described similarly.
- The Necronomicon, in turn, is a fictional book from the horror stories written by H. P. Lovecraft.