Ruins of Timedelle - The Fire Song Chronicles, #3

The Fire Song Chronicles Book 3 "By my honour, by my blood, " Torin felt a stir of pride as he spoke the Tournament Oath. Prince Torin and his team have arrived on Timedelle to compete in the Tournament, an ultimate test of skills and bravery, against the other Kingdoms. When an unexpected attack disrupts the Tournament and damages the Pathway, it reveals a new threat rising out of the scorched desert unlike anything they have encountered before. As a result all the Kingdoms, including the Erifs, are faced with a choice:Combine their forces to stop this new threat or perish.
  Now Torin is confronted with the impossible task of not only fighting alongside his people's greatest enemy, but trusting them with his friends' lives.