Forbidding Watchtower (ULG) from Urza's Legacy, available at 401 Games Canada.

• Rarity: Uncommon
• Finish: Normal
• Artist: Mark Brill
• Card Text:
  Forbidding Watchtower comes into play tapped.
  T: Add one white mana to your mana pool.
  1W: Forbidding Watchtower becomes a 1/5 white creature until end of turn. This creature still counts as a land.