Most played cards in Ruhan of the Fomori:

5 Decks
Arid Mesa
5 copies - 1 average
Flooded Strand
5 copies - 1 average
Brainstorm
5 copies - 1 average
Sacred Foundry
5 copies - 1 average
Force of Will
5 copies - 1 average
Scalding Tarn
5 copies - 1 average
Miscalculation
5 copies - 1 average
Mana Leak
5 copies - 1 average
Counterspell
5 copies - 1 average
Supreme Verdict
5 copies - 1 average
Swords to Plowshares
5 copies - 1 average
Steam Vents
5 copies - 1 average
Polluted Delta
5 copies - 1 average
Council's Judgment
5 copies - 1 average
Ponder
5 copies - 1 average
Windswept Heath
5 copies - 1 average
Fact or Fiction
5 copies - 1 average
Bloodstained Mire
5 copies - 1 average
Command Tower
5 copies - 1 average
Dig Through Time
4 copies - 0.8 average