Asylum in Firelight. The Vast Collective Series, #3

Nox has won. Rayne is his captive. Every hour, her prison draws enough blood from her to keep the conduit between Earth and Cinder open - a bridge enabling humanity's enslavement to Nox's people, the Icari. Nox knows his plans are twisted and wrong. He is wrong. But he will stop at nothing to claim his revenge. Once Rayne escapes, it's all out war, and she is the ultimate weapon. It comes at a cost, but nothing will stop Rayne from saving her people - a determination she and Nox share.
The heroes have to win to free Earth and unite with the Vast Collective for trade, defenses, and biological enhancements. If the Progeny fail, Nox's plans to incinerate Earth to ash will succeed - and he'll burn Cinder with it, changing the landscape of the galaxy forever. Killing Nox isn't revenge. It's justice. For Rayne. For her people. And for every other planet he has reduced to nothing.