Strange Inversion (CHK) from Champions of Kamigawa, available at 401 Games Canada.

• Rarity: Uncommon
• Finish: Normal
• Artist: Khang Le
• Card Text:
  Switch target creature’s power and toughness until end of turn.
  Splice onto Arcane 1R (As you play an Arcane spell, you may reveal this card from your hand and pay its splice cost. If you do, add this card’s effects to
  that spell.)