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I know it’s an older series; I believe the publication date was around the '80s or early '90s. The main focus of the books are these magic rocks granting certain powers (lightning, truth seeking, damage absorption—I believe—etc.), and the original stone found is called something like "lamb shabah." It’s all set in early medieval times era. I think it’s called the "Lightning [something]," but I know it’s not The Lightning Thief. After the main character finds the first stone and starts to use it, her main arm (I think her left one) gets heavily scarred; however, the other stones don’t leave as bad marks on their users. Any help identifying what book series this is, or who the author is, will be greatly appreciated, as I would love to read it again. Thanks.