Murmuration (BLC) from Bloomburrow Commander, available at 401 Games Canada.

• Rarity: Rare
• Finish: Normal
• Artist: Xabi Gaztelua
• Card Text:
  Birds you control get +1/+1 and have vigilance.
  At the beginning of your end step, for each spell you've cast this turn, create a 1/2 blue Bird creature token with flying named Storm Crow.