Most played cards in Ton:

1 Decks
Barbed Sextant
4 copies - 4 average
Sungrass Egg
4 copies - 4 average
Phantom Nishoba
4 copies - 4 average
Living Wish
4 copies - 4 average
Mishra's Helix
4 copies - 4 average
Decree of Justice
4 copies - 4 average
Swords to Plowshares
4 copies - 4 average
Urza's Power Plant
4 copies - 4 average
Urza's Mine
4 copies - 4 average
Urza's Tower
4 copies - 4 average
Circle of Protection: Red
3 copies - 3 average
Crop Rotation
3 copies - 3 average
Krosan Tusker
3 copies - 3 average
Naturalize
2 copies - 2 average
Emerald Charm
2 copies - 2 average
Wasteland
2 copies - 2 average
Triskelion
2 copies - 2 average
Wall of Blossoms
2 copies - 2 average
Brushland
2 copies - 2 average
Treetop Village
2 copies - 2 average