Leechridden Swamp (HOP) from Planechase, available at 401 Games Canada.

• Rarity: Uncommon
• Finish: Normal
• Artist: Lars Grant-West
• Card Text:
  (T: Add B to your mana pool.)
  Leechridden Swamp enters the battlefield tapped.
  B, T: Each opponent loses 1 life. Activate this ability only if you control two or more black permanents.