Most played cards in Merfolks:

1 Decks
Mutavault
4 copies - 4 average
Aether Vial
4 copies - 4 average
Gut Shot
4 copies - 4 average
Unified Will
4 copies - 4 average
Tectonic Edge
4 copies - 4 average
Cursecatcher
4 copies - 4 average
Spreading Seas
4 copies - 4 average
Silvergill Adept
4 copies - 4 average
Master of Waves
4 copies - 4 average
Master of the Pearl Trident
4 copies - 4 average
Lord of Atlantis
4 copies - 4 average
Harbinger of the Tides
3 copies - 3 average
Spell Pierce
3 copies - 3 average
Merrow Reejerey
3 copies - 3 average
Vendilion Clique
2 copies - 2 average
Vapor Snag
2 copies - 2 average
Relic of Progenitus
2 copies - 2 average
Cavern of Souls
2 copies - 2 average
Minamo, School at Water's Edge
1 copies - 1 average
Oboro, Palace in the Clouds
1 copies - 1 average