Arboretum Elemental (GRN) from Guilds of Ravnica, available at 401 Games Canada.

• Rarity: Uncommon
• Finish: Normal
• Artist: James Paick
• 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.)
  Hexproof (This creature can't be the target of spells or abilities your opponents control.)