The Keeper's Price

From the back cover:
The lore of the planet of the Bloody Sun, Darkover, with its human and semi-human peoples, its science of emntal powers, its loves and hates, its feuds and favors -- all have grown into one of the greater classics of the imagination, comparable only to the Middle Earth of Tolkien.
For so deep and complex has been the creation of this worlds that readers have sought to fill in the unknown spots of its saga. They, forming the Friends of Darkover, have joined with Marion Zimmer Bradley to create this anthology of new stories of Darkover, written by its most talented followers.
Here are stories that span the whole of Darkover history -- from the days after the original landfall, through the Ages of Chaos, the Pact of the Comyn, and the coming of the Terrans. Included are three original stories by Marion Zimmer Bradley and her editorial commentaries on each story.