Stalking Stones (MRD) from Mirrodin, available at 401 Games Canada.

• Rarity: Uncommon
• Finish: Normal
• Artist: David Day
• Card Text:
  T: Add 1 to your mana pool.
  6: Stalking Stones becomes a 3/3 artifact creature that's still a land. (This effect doesn't end at end of turn.)