Tanith Lee 
Winter Players [EPUB ebook] 

She distrusted him at first, not least because she knew his words were lies. "Call me Grey, " he said, but that was not his name. Fear gripped her like a hand.No one but the priestess could look upon the relics: the Ring, the Jewel and the Bone. It was for the bone that this grey stranger had come. He was like a thief, but she realized with a sinking heart that he was armed with as much magic as herself, and maybe more.