The Last Mortal Bond written by Brian Staveley is the last book in the Chronicle of the Unhewn Throne trilogy.
Annur is being threatened by the ancient Csestriim and their desire to kill the old Gods that walk the earth again. The whole of the Urghul nation is at their door, their aim to spread their pain-worship across the lands, the easy way, or the hard way. Kettral are pitted against Kettral, brother against sister. War is fought in every corner of the once great Empire, and the three Malkeenian siblings are at the very heart of it.