Mobilized District (CMM) from Commander Masters, available at 401 Games Canada.

• Rarity: Rare
• Finish: Normal
• Artist: Jedd Chevrier
• Card Text:
  T: Add C.
  4: Mobilized District becomes a 3/3 Citizen creature with vigilance until end of turn. It's still a land. This ability costs 1 less to activate for each legendary creature and planeswalker you control.