Most played cards in Merfolks:

33 Decks
Lord of Atlantis
132 copies - 4 average
Daze
129 copies - 3.91 average
Winter Orb
126 copies - 3.82 average
Gush
122 copies - 3.7 average
Annul
94 copies - 2.85 average
Foil
91 copies - 2.76 average
Counterspell
78 copies - 2.36 average
Merfolk Looter
72 copies - 2.18 average
Waterfront Bouncer
70 copies - 2.12 average
Tidal Warrior
65 copies - 1.97 average
Blue Elemental Blast
62 copies - 1.88 average
Chill
57 copies - 1.73 average
Gaea's Skyfolk
56 copies - 1.7 average
Quirion Dryad
56 copies - 1.7 average
Rootwater Diver
54 copies - 1.64 average
Yavimaya Coast
50 copies - 1.52 average
Tormod's Crypt
48 copies - 1.45 average
Stifle
48 copies - 1.45 average
Portent
47 copies - 1.42 average
Hydroblast
39 copies - 1.18 average