Frontier Siege (C17) from Commander 2017, available at 401 Games Canada.

• Rarity: Rare
• Finish: Normal
• Artist: James Ryman
• Card Text:
  As Frontier Siege enters the battlefield, choose Khans or Dragons.
  • Khans — At the beginning of each of your main phases, add GG to your mana pool.
  • Dragons — Whenever a creature with flying enters the battlefield under your control, you may have it fight target creature you don't control.