Elemental Mastery (NEC) from Neon Dynasty Commander, available at 401 Games Canada.

• Rarity: Rare
• Finish: Normal
• Artist: Cyril Van Der Haegen
• Card Text:
  Enchant creature
  Enchanted creature has "T: Create X 1/1 red Elemental creature tokens with haste, where X is this creature's power. Exile them at the beginning of the next end step."