Most played cards in 4c:

1 Decks
Wasteland
4 copies - 4 average
Verdant Catacombs
4 copies - 4 average
Pyroblast
4 copies - 4 average
Force of Vigor
4 copies - 4 average
Deathrite Shaman
4 copies - 4 average
Collector Ouphe
3 copies - 3 average
Dark Confidant
3 copies - 3 average
Mindbreak Trap
3 copies - 3 average
Wrenn and Six
3 copies - 3 average
Bayou
3 copies - 3 average
Assassin's Trophy
3 copies - 3 average
Abrupt Decay
3 copies - 3 average
Ragavan, Nimble Pilferer
3 copies - 3 average
Wooded Foothills
2 copies - 2 average
Tarmogoyf
2 copies - 2 average
Opposition Agent
2 copies - 2 average
Taiga
2 copies - 2 average
Surgical Extraction
2 copies - 2 average
Lightning Bolt
2 copies - 2 average
Endurance
2 copies - 2 average