Falling Sky By Hair, David

Romara Challys and her Falcons have suffered for the truth, enduring vast journeys across a disintegrating world to uncover the suicidally destructive nature of elobyne, the energy crystals that are both the magical power upholding the Triple Empire, and the reason that same empire is racing toward environmental catastrophe. They have found new allies, other ways to channel magic, and exposed a deadly cabal of puppet-masters - the "angelic" Alephi - who secretly rule the empire.

Those successes will be their destruction.

Alarmed by the Falcons' discoveries, the immortal Alephi are stepping out of the shadows and unleashing their long-held dream: a centuries-old doomsday prophecy that will leave them the undisputed masters of a whole new world, while Talmont and the rest of the empire are left in ash and ruin.

The End isn't just nigh . . . it's now.