The Wind Riders by Kris Kramer

The Wind Riders. Fabled pirates, who sail the skies on magic airships, protecting the weak and harassing the tyrannical Clerics who rule the nearby city of Tyr. Their very name conjures up dreams of freedom and whispers of hope amongst the Tyran slaves forced to mine treacherous caves and mountains for the only known source of magic in the world. That is, until the Wind Riders are attacked and nearly destroyed by Tyr, who has somehow managed to build an airship of its own.

With many of their ships destroyed and their people dead, the surviving Wind Riders are forced to send a small group of volunteers into the heart of Tyr, the den of their hated enemies, to find allies who can help them continue to fly their remaining ships. Failure would mean certain death for everyone ever known as a Wind Rider, as Tyr is busy preparing their next attack, one that will eradicate the Wind Riders from existence.