Most played cards in Prison Song:

4 Decks
Swords to Plowshares
16 copies - 4 average
Disenchant
16 copies - 4 average
Tundra
15 copies - 3.75 average
Howling Mine
15 copies - 3.75 average
Icy Manipulator
14 copies - 3.5 average
Winter Orb
14 copies - 3.5 average
Relic Barrier
14 copies - 3.5 average
Fellwar Stone
12 copies - 3 average
Tropical Island
12 copies - 3 average
Power Sink
10 copies - 2.5 average
Armageddon
9 copies - 2.25 average
Titania's Song
9 copies - 2.25 average
Savannah
8 copies - 2 average
Wrath of God
8 copies - 2 average
Dust to Dust
8 copies - 2 average
Blue Elemental Blast
6 copies - 1.5 average
Mishra's Workshop
5 copies - 1.25 average
Strip Mine
5 copies - 1.25 average
Tranquility
5 copies - 1.25 average
Time Walk
4 copies - 1 average