Traitor's Moon, Vol. 3 » (Reprint)

As the war between Pleminar and Skala continues, there are growing rumors that Skala's ancient ally, Mycena, is about to join with the wealthier Pleminar, cutting Skala off from all trade routes. Now Alec and Seregil are sent on their most daring mission yet: convince the people of Aurenen to join Skala and end the war.

Locus - Carolyn Cushman

...[A]n entertaining tale of conspiracy, murder, magic, diplomacy, and an emotion-filled exile's return.