Hardened Scales is a rare Enchantment card from Khans of Tarkir Promos (PKTK), collector number 133s. Current market price: — (foil $9.15), TCGplayer market prices via Scryfall.
If one or more +1/+1 counters would be put on a creature you control, that many plus one +1/+1 counters are put on it instead.