This is book number 3 in the Heartland Trilogy series.
Blood will water the corn...
It's been a year since the Saranyu flotilla fell from the sky, and life in the Heartland has changed. Gone are the Obligations and the Harvest Home festivals. In their place is a spate of dead towns, the former inhabitants forced into mechanical bodies to serve the Empyrean--and crush the Heartland.
When Cael awakens from a Blightborn sleep, miles away from the world he remembers, he sets out across the Heartland to gather his friends for one last mission. As the mechanicals, a war flotilla, and a pack of feral Empyrean girls begin to close in on the Heartland, there isn't much time to make their next move. But if they can uncover a secret weapon in time, Cael and his friends might just find themselves with the power to save the world--or destroy it--resting in their hands.