Most played cards in Ruhan of the Fomori:

4 Decks
Arid Mesa
4 copies - 1 average
Ajani Vengeant
4 copies - 1 average
Counterspell
4 copies - 1 average
Sacred Foundry
4 copies - 1 average
Steam Vents
4 copies - 1 average
Flooded Strand
4 copies - 1 average
Spell Pierce
4 copies - 1 average
Mana Leak
4 copies - 1 average
Miscalculation
4 copies - 1 average
Brainstorm
4 copies - 1 average
Swords to Plowshares
4 copies - 1 average
Hallowed Fountain
4 copies - 1 average
Supreme Verdict
4 copies - 1 average
Council's Judgment
4 copies - 1 average
Ponder
4 copies - 1 average
Polluted Delta
4 copies - 1 average
Force of Will
4 copies - 1 average
Windswept Heath
4 copies - 1 average
Command Tower
4 copies - 1 average
Fact or Fiction
4 copies - 1 average