ISBN Ivory Tomb

The Ivory Tomb concludes the wildly original epic fantasy series bursting with intrigue and ambition, questioned loyalties, and broken magic that began with The Obsidian Tower.
The Dark Days have returned. The Demon of Carnage mercilessly cuts through villagers and armies. The Demon of Corruption rots the land. The Serene Empire and the Witch Lords race towards war. And in the middle of it all stands Rxyander, the Warden of Gloamingard.
Burdened by conflicting loyalties and guilt, Ryx searches desperately for a way to defeat the demons before the world she loves is completely destroyed. To find answers, she'll have to return to where it all started. . . the black tower at the heart of Gloamingard.
By blood the Door was opened and only by blood will the Dark Days end.