Most played cards in Prison Tron:

6 Decks
Serum Powder
24 copies - 4 average
Mystic Forge
24 copies - 4 average
Urza's Mine
24 copies - 4 average
Urza's Power Plant
24 copies - 4 average
Karn, the Great Creator
24 copies - 4 average
Expedition Map
24 copies - 4 average
Urza's Tower
24 copies - 4 average
Walking Ballista
24 copies - 4 average
Ensnaring Bridge
24 copies - 4 average
Chalice of the Void
24 copies - 4 average
Spellskite
24 copies - 4 average
Urza's Saga
18 copies - 3 average
Welding Jar
13 copies - 2.17 average
Eldrazi Temple
12 copies - 2 average
Thought-Knot Seer
12 copies - 2 average
Sorcerous Spyglass
12 copies - 2 average
Pithing Needle
8 copies - 1.33 average
Torpor Orb
8 copies - 1.33 average
Gemstone Caverns
8 copies - 1.33 average
Inventors' Fair
8 copies - 1.33 average