Whiplash Trap (DDN) from Duel Decks: Speed vs. Cunning, available at 401 Games Canada.

• Rarity: Common
• Finish: Normal
• Artist: Zoltan Boros & Gabor Szikszai
• Card Text:
  If an opponent had two or more creatures enter the battlefield under his or her control this turn, you may pay U rather than pay Whiplash Trap's mana cost.
  Return two target creatures to their owners' hands.