Traitor's Knot (War of Light and Shadow): Alliance of Light Book Four

Arithon, Master of Shadow, has mastered the maze and achieved self-redemption. Now he's the guest of the formidable Sorcerer, Davien the Betrayer, an enigmatic recluse, and a peril in his own right. No faction knows how that influence will try Arithon's recovered mage power, or the new depths that have wakened a latent, rogue talent for prescience. Relentless enemies stop at nothing to achieve his downfall, but Arithon, opts for the most dangerous course. Heart and mind, he dedicates himself not to kill, though allies and enemies muster for war, single mindedly blind to the consequence.