Books like Jewel of the Endless Erg

After surviving Skyhold's deadly labyrinth, Hugh and his friends are looking forwards to an uneventful summer. Their teacher Alustin has chartered a sandship for a training expedition into the vast sea of sand known as the Endless Erg, aiming for the wealthy and powerful desert city of Theras Tel. Hugh's happier than he's been in a long, long time, and he's quite excited for the fresh air, sunshine, and quiet. Of course, given Hugh's luck, their summer is going to be anything but quiet. They're about to be plunged into a morass of pirates, monsters, warring cults, flesh-tearing sandstorms, and a conspiracy against Indris Stormbreaker, the dragon queen of Theras Tel herself. At least Hugh's going to get plenty of fresh air and sunshine.