Sunderflock (ECL) from Lorwyn Eclipsed, available at 401 Games Canada.

• Rarity: Rare
• Finish: Normal
• Artist: Caio Monteiro
• Card Text:
  This spell costs X less to cast, where X is the greatest mana value among Elementals you control.
  Flying
  When this creature enters, if you cast it, return all non-Elemental creatures to their owners' hands.