Splinter, Aging Champion is a rare Legendary Creature — Mutant Ninja Rat card from Teenage Mutant Ninja Turtles Eternal (TMC), collector number 104. Current market price: $0.67, TCGplayer market prices via Scryfall.
When Splinter enters, destroy up to one target tapped creature. When Splinter leaves the battlefield, you and another target player each draw a card.