The Traitor Son Cycle #5: The Fall of Dragons book by Miles Cameron

The Red Knight's final battle lies ahead . . . but there's a whole war still to fight first. He began with a small company, fighting the dangerous semi-mythical creatures which threatened villages, nunneries and cities. But as his power - and his forces - grew, so the power of the enemy he stood against became ever more clear. Not the power of men . . . but that of gods, with thousands of mortal allies. Never has strategy been more important, and this war will end where it started: at Lissen Carak. But to get there means not one battle, but many - to take out the seven armies which stand against them and force Ash, the huge black dragon, to finally take to the field himself . . . Published By Gollancz on 2017-10-19