Boxing Ring (NCC) from New Capenna Commander, available at 401 Games Canada.

• Rarity: Rare
• Finish: Normal
• Artist: James Paick
• Card Text:
  Whenever a creature enters the battlefield under your control, it fights up to one target creature you don't control with the same mana value.
  T: Create a Treasure token. Activate only if you control a creature that fought this turn.