Well of Witches — J.A. White

Kan and Taff have finally reached the World beyond the island, and it's in total turmoil. As the Spider Queen lures new witches to her side, an army of graycloaks sets out on a crusade to destroy all magic, led by the vicious witch hunter, Timoth Clen. Kan and Taff have to undo the terrible curse on their father before it's too late . . . but only Grace Stone has the power to reverse her Last Spell. If Kara and Taff want to save their father, they must rescue their old enemy from the Well of Witches first.

The Well is corrupted by dark magic and unthinkable creatures called the Faceless that rule over the captive witches. Kara and Taff will discover secrets of the Well -- an ancient magic school, an unhappy princess, and the Changing Place -- but will they find Grace?