Fallowblade : Book Four of the Crowthistle Chronicles

Weapons glitter, men's voices are raised in battle-song and bright banners crack and flap in a sharp breeze; armies of steel and bronze are marching to war as the ruthless king of the southern realm executes his plan to seize dominion over the Four Kingdoms. With Tir's most powerful protectors slain by treachery and the defenders scattered, it appears nothing can stand in the tyrant's way. Asrathiel, summoner of storms, called 'Weatherwitch' by her wayward, eldritch companion, aids the defenders as best she can, but the invading armies are pushing further north and it seems that all is lost ...Until a new peril unexpectedly looms; a far more dangerous and deadly menace that threatens not merely the balance of power, but the entire human race ...'Dart-Thornton conjures up her world of Tir in the luminous yet hard-edged manner of Jack Vance and Mary Gentle' Washington Post