Most played cards in Red Prison:

1 Decks
Abrade
4 copies - 4 average
Ancient Tomb
4 copies - 4 average
Null Rod
4 copies - 4 average
Simian Spirit Guide
4 copies - 4 average
Leyline of the Void
4 copies - 4 average
Blood Moon
4 copies - 4 average
Magus of the Moon
4 copies - 4 average
Wasteland
4 copies - 4 average
City of Traitors
4 copies - 4 average
Goblin Rabblemaster
4 copies - 4 average
Ensnaring Bridge
3 copies - 3 average
Pyroblast
3 copies - 3 average
Pyrostatic Pillar
3 copies - 3 average
Shattering Spree
3 copies - 3 average
Chandra, Torch of Defiance
3 copies - 3 average
Fiery Confluence
2 copies - 2 average
Grafdigger's Cage
2 copies - 2 average
Mox Ruby
1 copies - 1 average
Black Lotus
1 copies - 1 average
Chalice of the Void
1 copies - 1 average