The Grand Grimoire is a book that describes all magic spells in great detail, including what magic gems need to be used for a specific spell.
In order for a witch to cast a magic spell, two things are needed:
- They need to posses a Talea Magica.
- They need to insert the correct magical gem in the Talea Magica.
After these conditions have been met, a witch may cast a spell by reciting the correct incantation.
The conditions above, however, do not apply to the Great Witch Bezella, who can freely use any magic without even possessing a Talea Magica.
In reality, the conditions for using magic have been invented in order to allow the Shades to do their work properly. The magic gems limit the amount of material they have to take, and the enchantment lets them know when to take action.