Most played cards in 4c Tron:

3 Decks
Urza's Mine
12 copies - 4 average
Urza's Tower
12 copies - 4 average
Prophetic Prism
12 copies - 4 average
Urza's Power Plant
12 copies - 4 average
Mulldrifter
12 copies - 4 average
Moment's Peace
11 copies - 3.67 average
Expedition Map
11 copies - 3.67 average
Hydroblast
8 copies - 2.67 average
Mnemonic Wall
7 copies - 2.33 average
Gorilla Shaman
6 copies - 2 average
Thornwood Falls
6 copies - 2 average
Mystical Teachings
6 copies - 2 average
Dinrova Horror
5 copies - 1.67 average
Pyroblast
5 copies - 1.67 average
Shimmering Grotto
5 copies - 1.67 average
Forbidden Alchemy
5 copies - 1.67 average
Simic Signet
5 copies - 1.67 average
Prohibit
5 copies - 1.67 average
Swiftwater Cliffs
5 copies - 1.67 average
Ghostly Flicker
5 copies - 1.67 average