Hardened Scales is a rare Enchantment card from Wilds of Eldraine: Enchanting Tales (WOT), collector number 55. Current market price: $4.64 (foil $10.16), 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.