Land of the burning sands - Rachel Neumeier

In the aftermath of a brutal war, Gereint of Casmantium watches his city crumble. He knows little of how his king sought, unwisely, to use griffins as pawns in a human conflict. Yet Gereint does know that his kingdom's defeat offers him a chance to escape from servitude.

But now that the griffins find themselves in a position of strength, they are not inclined to forgive, and the entire kingdom finds itself in deadly peril. Willing or not, Gereint will find himself caught up in a desperate struggle between the griffins and the last remaining Casmantian mage.

Time is short, for the fiery wind of the griffins is already burying Casmantium beneath burning sands . . .