Holdout Settlement (OGW) from Oath of the Gatewatch, available at 401 Games Canada.

• Rarity: Common
• Finish: Normal
• Artist: Kieran Yanner
• Card Text:
  T: Add C to your mana pool. (C represents colorless mana.)
  T, Tap an untapped creature you control: Add one mana of any color to your mana pool.