Most played cards in Gruul:

3 Decks
Lightning Bolt
12 copies - 4 average
Burning-Tree Emissary
12 copies - 4 average
Pyroblast
10 copies - 3.33 average
Nest Invader
8 copies - 2.67 average
Living Totem
8 copies - 2.67 average
Thermo-Alchemist
8 copies - 2.67 average
Nettle Sentinel
8 copies - 2.67 average
Electrickery
8 copies - 2.67 average
Dynacharge
8 copies - 2.67 average
Scatter the Seeds
8 copies - 2.67 average
Rugged Highlands
8 copies - 2.67 average
Sprout Swarm
8 copies - 2.67 average
Khalni Garden
8 copies - 2.67 average
Essence Warden
6 copies - 2 average
Mogg War Marshal
6 copies - 2 average
Spidersilk Armor
4 copies - 1.33 average
Flame Slash
4 copies - 1.33 average
Might of the Masses
4 copies - 1.33 average
Ash Barrens
4 copies - 1.33 average
Tin Street Hooligan
4 copies - 1.33 average