Devouring Light (GK1) from GRN Guild Kit, available at 401 Games Canada.

• Rarity: Uncommon
• Finish: Normal
• Artist: Pete Venters
• Card Text:
  Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for 1 or one mana of that creature's color.)
  Exile target attacking or blocking creature.