Well, this is really a time-capsule from the late eighties. Very female-centric, it describes a … tribe of women with magic that brings to life a doppelganger dark sister, but only in the shadows and moonlight.
The main character may be destined to lead them to a new prominent role in the world through battle, but maybe at the expense of the core philosophies of their way of life.
The tone is fairly mythical and mystic. Like a fairy tale.