Unquenchable Fury is a rare Enchantment — Aura card from Neon Dynasty Commander (NEC), collector number 23. Current market price: $0.41, TCGplayer market prices via Scryfall.
Enchant creature Enchanted creature has "Whenever this creature attacks, it deals X damage to defending player, where X is the number of cards in their hand." When this Aura is put into your graveyard from the battlefield, return it to your hand.