Mage's Blood: Book 1

Most of the time the Moontide Bridge lies deep below the sea, but every 12 years the tides sink and the bridge is revealed, its gates open for trade. The Magi are hell-bent on ruling this new world, and for the last two Moontides they have led armies across the bridge on crusades of conquest. Now the third Moontide is almost here and, this time, the people of the East are ready for a fight...but it is three seemingly ordinary people who will decide the fate of the world.