Calciform Pools (TSP) from Time Spiral, available at 401 Games Canada.

• Rarity: Uncommon
• Finish: Normal
• Artist: Darrell Riche
• Card Text:
  T: Add 1 to your mana pool.
  1, T: Put a storage counter on Calciform Pools.
  1, Remove X storage counters from Calciform Pools: Add X mana in any combination of W and/or U to your mana pool.