Most played cards in Machinehead:

1 Decks
Duress
4 copies - 4 average
Dark Ritual
4 copies - 4 average
Hypnotic Specter
4 copies - 4 average
Sulfurous Springs
4 copies - 4 average
Bloodstained Mire
4 copies - 4 average
Wasteland
4 copies - 4 average
Lightning Bolt
4 copies - 4 average
Plague Spitter
3 copies - 3 average
Rain of Tears
3 copies - 3 average
Black Knight
3 copies - 3 average
Pyroblast
3 copies - 3 average
Terminate
3 copies - 3 average
Tainted Peak
2 copies - 2 average
Shattering Pulse
2 copies - 2 average
Withered Wretch
2 copies - 2 average
Engineered Plague
2 copies - 2 average
Cursed Scroll
2 copies - 2 average
Phyrexian Arena
2 copies - 2 average
Phyrexian Scuta
2 copies - 2 average
Nantuko Shade
2 copies - 2 average