Requiting Hex (ECL) from Lorwyn Eclipsed, available at 401 Games Canada.

• Rarity: Uncommon
• Finish: Normal
• Artist: Randy Gallegos
• Card Text:
  As an additional cost to cast this spell, you may blight 1. (You may put a
  -1/-1 counter on a creature you control.)
  Destroy target creature with mana value 2 or less. If this spell's additional cost was paid, you gain 2 life.