Most played cards in 4c Tron:

4 Decks
Urza's Power Plant
16 copies - 4 average
Urza's Tower
16 copies - 4 average
Urza's Mine
16 copies - 4 average
Prophetic Prism
16 copies - 4 average
Mulldrifter
16 copies - 4 average
Expedition Map
13 copies - 3.25 average
Moment's Peace
12 copies - 3 average
Hydroblast
10 copies - 2.5 average
Swiftwater Cliffs
9 copies - 2.25 average
Mnemonic Wall
9 copies - 2.25 average
Pyroblast
8 copies - 2 average
Thornwood Falls
7 copies - 1.75 average
Gorilla Shaman
7 copies - 1.75 average
Pulse of Murasa
7 copies - 1.75 average
Mystical Teachings
7 copies - 1.75 average
Forbidden Alchemy
7 copies - 1.75 average
Flame Slash
6 copies - 1.5 average
Condescend
6 copies - 1.5 average
Ghostly Flicker
6 copies - 1.5 average
Prohibit
6 copies - 1.5 average