Most played cards in U/R/x Tron:

1 Decks
Urza's Mine
4 copies - 4 average
Steam Vents
4 copies - 4 average
Volcanic Hammer
4 copies - 4 average
Urza's Power Plant
4 copies - 4 average
Urza's Tower
4 copies - 4 average
Giant Solifuge
4 copies - 4 average
Annex
4 copies - 4 average
Rune Snag
4 copies - 4 average
Simic Sky Swallower
4 copies - 4 average
Izzet Signet
4 copies - 4 average
Remand
4 copies - 4 average
Compulsive Research
4 copies - 4 average
Breeding Pool
4 copies - 4 average
Shivan Reef
3 copies - 3 average
Wildfire
3 copies - 3 average
Repeal
3 copies - 3 average
Cancel
2 copies - 2 average
Confiscate
2 copies - 2 average
Tidings
2 copies - 2 average
Simic Signet
2 copies - 2 average