Faces (The Masks of Aygrima)

Final novel in EC Blake's dystopian fantasy trilogy, The Masks of Aygrima

The Masks of Aygrima is set in a land where people are forced to wear spell-imbued Masks that reveal any traitorous thoughts they have about their ruler, the Autarch. 
 
Mara Holdfast is a young woman gifted with the ability to see and use all the colors of magic. Two other people share this talent: the Autarch, who draws upon the very life-force of his subjects to fuel his existence and retain his control over the kingdom; and the legendary Lady of Pain and Fire, the only person who has ever truly challenged the Autarch’s despotic reign.
 
After a devastating battle that takes a dreadful toll on both the rebel unMasked Army and the forces of Prince Chell, their ally from across the sea, Mara and her fellow survivors have no one to turn to for help but the Lady of Pain and Fire.
 
As the Lady leads them to her haven beyond the mountain borders of the kingdom, Mara feels that she has found the one person who truly understands her, a mentor who can teach her to control and use her power for the greater good. Together, they may be able to at last free Agryma from the Autarch’s rule.
 
Living within the Lady’s castle, cut off from her friends in the village far below, Mara immerses herself in her training. Still, she can’t entirely escape from hearing dark hints about the Lady, rumors that the Lady may, in her own way, be as ruthless as the Autarch himself.
 
Yet it is not until they begin their campaign against the Autarch that Mara discovers where the real danger lies. Driven by the Lady’s thirst for revenge, will Mara and all her friends fall victim in a duel to the death between two masters of magic?