Priestess of Avalon by Marion Zimmer Bradley and Diana L. Paxson. It’s a wonderful fantasy full of druids and magic and all things imaginative. It’s written by the same women who wrote The Mists of Avalon. To my knowledge you don’t need to read one, to read the other. But really, is there any reason you shouldn’t pick them both up now? Well perhaps not both at the same time… I’ll understand the one then the other method.