The Dragonbards

Dragonbards Trilogy, Book 3. Only the dragonbards and their singing dragons have the power to unite the people and animals of Tirror into an army that can break the Dark's hypnotic hold over the world. Before their leader Tebriel can challenge the hordes gathering for the final battle, he must confront the dark lord Quazelzeg face to face in the Castle of Doors, a warp of time and space.

From the reviews:

"Once again Murphy demonstrates a fine sense of storytelling, high adventure, scene setting, and characterization—human, animal, and evil monster. And her dragons remain some of the most appealing in contemporary fantasy." —ALA Booklist

"The concluding volume of the author's generally acclaimed Dragonbards trilogy . . . assumes a harrowing narrative pace that builds to a grand, good-over-evil finale. . . . This is rollicking high fantasy." —Christian Science Monitor