Winter's Night 
World Enchantment
Whenever a player taps a snow land for mana, that player adds one mana of any type that land produced. That land doesn't untap during its controller's next untap step.
Legality
standardNOT LEGALpioneerNOT LEGALmodernNOT LEGALlegacyLEGALvintageLEGALcommanderLEGAL