Underground Sea (3ED) from Revised Edition, available at 401 Games Canada.

• Rarity: Rare
• Finish: Normal
• Artist: Rob Alexander
• Card Text:
  T: Add either B or U to your mana pool.Counts as both swamp and islands and is affected by spells that affect either. If a spell destroys one of these land types, this card is destroyed; if a spell alters one of these land types, the other land type is unaffected.