Exploding Barrel (TMC) from Teenage Mutant Ninja Turtles Eternal, available at 401 Games Canada.

• Rarity: Rare
• Finish: Normal
• Artist: Eliz Roxs
• Card Text:
  T: Add one mana of any color. Put a pressure counter on this artifact.
  8, T, Sacrifice this artifact: It deals 20 damage to target creature. This ability costs 1 less to activate for each pressure counter on this artifact. Activate only as sorcery.