The Final Gauntlet - Greystone-In-Training, #3

The Daughters of Salem have returned. A doorway was opened and a threat from the earliest days of Portents has found its way home. The Daughters have a clear mission: to use the power of the doorkeeper and awaken a terrible darkness on the world. Soriya stands alone to face the threat. To do so, she must protect the magic-wielding doorkeeper-a woman in a desperate search to find her past. There is more at stake for Soriya, though, as Mentor levels one final test upon her.
Should she pass, Soriya will at last earn the mantle of the Greystone. If she fails, however, all of Portents may succumb to the darkness within their souls. Her greatest challenge is only the beginning as the secrets of the city come to light in the epic final chapter of the Greystone-in-Training trilogy.