Most played cards in Scion of the Ur-Dragon:

4 Decks
Verdant Catacombs
4 copies - 1 average
Reanimate
4 copies - 1 average
Polluted Delta
4 copies - 1 average
Marsh Flats
4 copies - 1 average
Windswept Heath
4 copies - 1 average
Liliana of the Veil
4 copies - 1 average
City of Brass
4 copies - 1 average
Elesh Norn, Grand Cenobite
4 copies - 1 average
Iona, Shield of Emeria
4 copies - 1 average
Arid Mesa
4 copies - 1 average
Command Tower
4 copies - 1 average
Animate Dead
4 copies - 1 average
Flooded Strand
4 copies - 1 average
Wooded Foothills
4 copies - 1 average
Demonic Tutor
4 copies - 1 average
Mystical Tutor
4 copies - 1 average
Entomb
4 copies - 1 average
Thoughtseize
4 copies - 1 average
Underground Sea
4 copies - 1 average
Swords to Plowshares
4 copies - 1 average