Magic's Promise (The Last Herald-Mage Series, Book 2)

Groundbreaking epic fantasy series in Mercedes Lackey’s Valdemar universe • Lambda-Award winning novels with heartfelt high adventure and magic  
 
Wild magic is taking its toll on the land. Many Heralds and Herald-Mages have died fighting to preserve the peace. Even Vanyel, the most powerful of the Herald-Mages is almost at the end of his strength, in need of a respite from the dual threats of war and dark magic.
 
But for Vanyel, there can be no rest. Not when his Companion, Yfandes, receives a summons which can’t be ignored—a desperate cry of a magical holocaust in the neighboring kingdom. Almost overwhelmed by the devastations they discover there, Herald-Mage and Companion must try to unravel this tragic mystery.
 
Is the young Prince Tashir, a newly Chosen Herald who can’t control his magic, responsible for the destruction? Or is Tashir a pawn in a deeper, more deadly game—and, if so, will Vanyel be able to find and defeat the true destroyer before this master of dark powers can strike again?