Gwen's spellbook, or her Grimoire, as she refers to it, is a purple and gold miniature spellbook which previously belonged to  Charmcaster. It was first seen in .
A Change of Face
Aquata Risa Spackwata
Bellum Ocorro Mazzora
Botigs Zaborito Carpis Nebegear Gais Liphan Intruders Utien
Estotei Quasai Integumentum Imatari Proximum
Fallum Quarca Daminigan
Imperium Im Mentum
Rest Ituo Nowitus Wespinaetro Itus Vigoratus Perwita
Saphirius Expectorium Perpetua
Silicus Milez Sasitatio
Tara Tremmo Eradico
Thanatis Icatis Exodus
Vadera Expectitiom Perpetuon
Via Esporow Via Esprolixas Capti Capters Few Sonmow Lenton Oway On Respicklas Lokis Lusses Via Astendus Ocultes Ienwuar
and Alien Force Ultimate Alien
Ben 10: Alien Force
Ben 10: Ultimate Alien
Ben 10: Omniverse
Ben 10 Ultimate Alien: Cosmic Destruction, Gwen used it to send Cooper home with the spell Meven Aweg.
Charmcaster hates Gwen for the fact that she kept the book.
In the original series, she claimed she was upset that Gwen hadn't made better use of it, that after a long time with the spell book Gwen still "hadn't taken off the training wheels".
Gwen used to bring her spellbook to school.
 In the original series, Gwen's spellbook was pocket size. Then in , it was bigger than her hands. In Alien Force , it was pocket-sized again.
Ben 10: Ultimate Alien In the original series and , Gwen's spellbook contained pictures of the spells, but in Omniverse Alien Force and Ultimate Alien, it was written in runes, which only people with knowledge of magic can read.
If the user concentrates whilst reading the spellbook, they'll seemingly absorb the magical power of the spellbook, amplifying their magical powers and granting them the ability of flight.
 Gwen's spellbook can create a forcefield for defense if something attempts to hit it.