Rise and Fall (Spirit Animals, Book 6) (6) / Schrefer, Eliot

Deep in the desert there sits a beautiful oasis, ruled by a monarch unlike any other in Erdas. His name is Cabaro, the Great Lion, and he reigns over a kingdom of animals, jealously guarding his golden talisman. No human has ever set foot in the Great Beast’s territory. The journey to his oasis is impossible.

As a team, Conor, Abeke, Meilin, and Rollan have achieved the impossible before. But now that team is broken—the friends scattered by a devastating betrayal. 
 
The young heroes and their spirit animals have already sacrificed much in their quest for the talismans. But with the world crumbling all around them—and a ruthless enemy opposing their every move—their greatest sacrifices are yet to come.