The Longest Journey[]
The fourth and most powerful grade of magic users, "able to shape magic, and to use it, by force of will alone." It requires a special gift and proper education.
Benrime Salmin tells April that she has the ability to become a powerful Artisan.
Dreamfall[]
In Dreamfall, Minstrum Magda tells Zoë Castillo (thinking she is a wayward Shifter) that her best bet to get home is to find an Artisan in the Magic Ghetto. She says an Artisan would be able to help focus Zoë's abilities, much in the same way that Cortez and later the White Dragon reborn can do for April.
April's fellow Rebel Na'ane is trained as an Artisan, and her pendulum swinging seems to do the trick in sending Zoë back - although with some curious results.