Sprout Swarm (FUT) from Future Sight, available at 401 Games Canada.

• Rarity: Common
• Finish: Normal
• Artist: Chippy
• Card Text:
  Convoke (Each creature you tap while playing this spell reduces its total cost by 1 or by one mana of that creature's color.)
  Buyback 3 (You may pay an additional 3 as you play this spell. If you do, put this card into your hand as it resolves.)
  Put a 1/1 green Saproling creature token into play.