Flight of the Phoenix — Dave Wolverton

When Alex O'Connell returns to Egypt to resume his training with Ardeth Bay, he expects the usual adventure -- fighting evil mummies, chasing bad guys through the desert, and riding his beloved camel, Stinkwad. But Ardeth Bay has something very different in mind. It is time for Alex to be tested. Alex discovers that battling nasty mummies is a whole lot easier than figuring out exactly what he's being tested on. All he knows is that it involves the egg of a Phoenix and that, if he fails, he will never be a true Medjai.