Feast of the Victorious Dead is a uncommon Enchantment card from March of the Machine: The Aftermath (MAT), collector number 80. Current market price: $0.29 (foil $0.48), TCGplayer market prices via Scryfall.
At the beginning of your end step, if one or more creatures died this turn, you gain that much life and distribute that many +1/+1 counters among any number of creatures you control.