Shadowplay — Jo Clayton

Now in ebook for the first time, the first book of Clayton's classic trilogy, Shadith's Quest 

Spacenapped when she stumbled on a kidnapping in progress, Shadith -- captive for centuries in the alien artifact known as the Diadem, now once again living in a human form -- finds herself the prisoner of Ginbiryol Seyirshi, a being who has instigated devastating wars on world after world purely to film and sell Limited Editions of the resulting violence, destruction, and death.

Along with two fellow humanoid prisoners, Shadith has been chosen to play a key role in Seyirshi's newest "production", serving as a demigod around whom the rebel forces will rally only to face a terrible doom. But prisoner though she is, Shadith has some unique resources of her own, and with these Diadem-mastered powers, she will do all she can to rewrite Seyirshi's script so that the people of this troubled planet as well as she and her fellow captives can win their freedom and put an end to Seyirshi's interstellar reign of terror...