Most played cards in Horde of Notions:

4 Decks
Savannah
4 copies - 1 average
Polluted Delta
4 copies - 1 average
Plateau
4 copies - 1 average
Windswept Heath
4 copies - 1 average
Watery Grave
4 copies - 1 average
Temple Garden
4 copies - 1 average
Tropical Island
4 copies - 1 average
Taiga
4 copies - 1 average
Stomping Ground
4 copies - 1 average
Steam Vents
4 copies - 1 average
Overgrown Tomb
4 copies - 1 average
Misty Rainforest
4 copies - 1 average
Flooded Strand
4 copies - 1 average
Swords to Plowshares
4 copies - 1 average
Badlands
4 copies - 1 average
Hallowed Fountain
4 copies - 1 average
Abrupt Decay
4 copies - 1 average
Marsh Flats
4 copies - 1 average
Arid Mesa
3 copies - 0.75 average
Volcanic Island
3 copies - 0.75 average