The Bitter Twins by Jen Williams (The Winnowing Flame Trilogy #2)
The Ninth Rain has fallen, the Jure’lia have returned, and with Ebora a shadow of its former self, the old enemy are closer to conquering Sarn than ever.
Tormalin the Oathless and the Fell-Witch Noon have their hands full dealing with the first war-beasts to be born in Ebora for nearly three hundred years. But these are not the great mythological warriors of old; hatched too early and with no link to their past lives, the war-beasts have no memory of the many battles they have fought and won, and no concept of how they can possibly do it again. The key to uniting them, according to the scholar Vintage, may lie in a part of Sarn no one really believes exists, but finding it will mean a dangerous journey at a time of war…
Meanwhile, Hestillion is trapped on board the corpse moon, forced into a strange and uneasy alliance with the Jure’lia queen. Something terrifying is growing up there, in the heart of the Behemoth, and the people of Sarn will have no defence against these new monsters.