Unquenchable Fury (NEC) from Neon Dynasty Commander, available at 401 Games Canada.

• Rarity: Rare
• Finish: Normal
• Artist: Livia Prima
• Card Text:
  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 Unquenchable Fury is put into your graveyard from the battlefield, return it to your hand.