Flight of Vengeance by Andre Norton

The Witch World is Grand Master Andre Norton's bestselling fantasy series. In STORMS OF VICTORY she began the most ambitious undertaking of her long and storied career, bringing to life the turbulent and pivotal events of the Witch World's greatest crisis. FLIGHT OF VENGEANCE is the book that Witch World fans have long awaited. Here, in two full-length novels, are the awesome power and terrible consequences of THE TURNING, told by the people whose lives were utterly changed by this cataclysmic event. Exile is the story of two outcasts thrust together by a monumental feat of magic, worked by the combined force of all the witches of Escarp to move mountains. The witches stopped the invasion by Pagar of Karsten, but their effort cost the witches dearly, killing many and striking powerless many others. A great upheaval uprooted families, destroyed nations, and wreaked havoc on the face of the world, unleashing powers thought long dead and gone. Exile is, most of all, the tale of Nolar, a witch who couldn't find her power until all others lost theirs. Magically summoned to rescue another, she discovered an enemy who, in his mind, would become a friend. Falcon Hope is the story of the Dalesfolk of Sea Keep and the falconers they hire to defend themselves. In crisis, the falcon band find themselves fighting with, instead of against, other Witch Worlders to defend one small part of their world against an otherworldly enemy.

This book is part of the "Witch World Series 3: The Turning" series.
Here are some other books from this series: