Queen of the Darkness - Anne Bishop (Book 3 in The Black Jewels Trilogy)

War is coming to the Shadow-Realm. To save millions of lives, Witch must sacrifice only one: hers.

Jaenelle, the long-prophesised Witch Queen, has finally healed, and emerged stronger than ever to claim her throne. But for centuries a taint has been creeping across the realms, corrupting those born into power. Now war is coming to the Shadow-Realm - and Witch is helpless to prevent it.

The Dreamweavers' webs show two paths. One will see the blood of millions spilled, the other will see the taint destroyed - and only one person needs to die. Her.