A Hope in Hell by Christopher G. Nuttall (epub) Heirs of Cataclysm Book 3
They hold the secret that could break the world… again.
John, Scout, and the rest of Joyce’s crew flee across the deserts and magical wastelands holding the plans to make motivators, devices that provide unlimited magical power to any mage.
Devices owned only by Greyshade, the man who saved the world after the apocalypse. Devices he blames for bringing the apocalypse in the first place. Devices he’ll do anything to keep secret.
Now, instead of bounty hunters, Greyshade is sending armies and magical assassins after them. And if that’s not enough, he’s leading this vast force himself.
Will John and his friends stand up against the greatest wizard in the world? Can they hold off all the assembled armies? Or is releasing the second apocalypse their only hope?