Most played cards in Vial Wizards:

3 Decks
Aether Vial
12 copies - 4 average
Chalice of the Void
12 copies - 4 average
Force of Will
12 copies - 4 average
Leyline of the Void
12 copies - 4 average
Dark Confidant
12 copies - 4 average
Voidmage Prodigy
12 copies - 4 average
Wasteland
11 copies - 3.67 average
Flooded Strand
10 copies - 3.33 average
Underground Sea
10 copies - 3.33 average
Engineered Explosives
9 copies - 3 average
Polluted Delta
9 copies - 3 average
Daze
9 copies - 3 average
Sage of Epityr
8 copies - 2.67 average
Martyr of Frost
7 copies - 2.33 average
Stifle
7 copies - 2.33 average
Pithing Needle
6 copies - 2 average
Tundra
4 copies - 1.33 average
Meddling Mage
4 copies - 1.33 average
Mindbreak Trap
4 copies - 1.33 average
Qasali Pridemage
4 copies - 1.33 average