Which sounds better - a prophetic mirror that usually tells the truth perfectly but occasionally flat out lies, or one that always tells mostly the truth, but with a false detail? The mirror can show anything, anywhere, and reveal any likely future. In one case, out of every 12 questions asked the mirror truthfully answers 11, and falsely answers 1. In the other case, the mirror's answers are mostly true, but with a false detail hidden therein.
In pre-Tepatic, ancient Milim, the Tsaltep - one of the early kings - receives several gifts from his personal god, the “Lord of Light,” such as an invincible suit made of demon’s skin, and a clairvoyant / prophetic mirror. Actually, for some “gifts,” including the mirror, he actually receives instructions for making the items. Due to an (unspecified) error, he doesn’t execute this correctly, and the supernatural being determines that the mirror will work, but because of the flawed process, the mirror’s prophecy will always be flawed. The mirror will be 11/12 correct. How this actually works out could be either (a) 11 out of 12 answers are correct and 1 is wrong, or (b) every answer is 11/12 correct.