Lamentation / Ken Scholes.

Enhanced descriptions from Syndetics:

An ancient weapon has completely destroyed the city of Windwir.   From many miles away, Rudolfo, Lord of the Nine Forest Houses, sees the horrifying column of smoke rising.  He knows that war is coming to the Named Lands.

Nearer to the Devastation, a young apprentice is the only survivor of the city -- he sat waiting for his father outside the walls, and was transformed as he watched everyone he knew die in an instant.

Soon all the Kingdoms of the Named Lands will be at each others' throats, as alliances are challenged and hidden plots are uncovered.

This remarkable first novel from an award-winning short fiction writer will take readers away to a new world -- an Earth so far in the distant future that our time is not even a memory; a world where magick is commonplace and great areas of the planet are impassable wastes. But human nature hasn't changed through the ages: War and faith and love still move princes and nations.