Lords of Deception - War of Four Kingdoms, #1

Emperors and kings thought it had been buried long ago: the Order of the Candlestone was defeated, the grim deeds of its assassins forgotten and its dangerous alchemy shunned. But Arasemis, an eccentric warrior-scholar, is determined to revive the Order and return the continent to its primitive origins, if he can control his apprentices. In his way is Arthan Valient, a young nobleman from a respected family who wrestles with providing honorable service to a weak king.
Thrust into a powerful position before he is ready, Arthan must navigate the political intrigue of a court in slow collapse, while avoiding Arasemis's new assassins. Milisend is the weak king's daughter, a princess who hides her love for a thief and her own passion for thievery. She secretly shuns the life of royalty, but the efforts of Arasemis and Arthan will change her life in ways she never expected.
And from within her emerges something she never knew she had. Arasemis, Arthan, Milisend, and their companions learn that help can be found in the most unlikely of places, even as the shadow of war looms across the continent. But trust is always elusive. Named a "Top 5 novel of the year" by Liviu Suciul, former co-editor of Fantasy Book Critic, see why Kirkus Reviews and others have compared this epic fantasy debut's depth and interesting characters to Game of Thrones.