Aurification is a rare Enchantment card from Onslaught (ONS), collector number 6. Current market price: $5.80 (foil $30.48), TCGplayer market prices via Scryfall.
Whenever a creature deals damage to you, put a gold counter on it. Each creature with a gold counter on it is a Wall in addition to its other creature types and has defender. (Those creatures can't attack.) When this enchantment leaves the battlefield, remove all gold counters from all creatures.