Most played cards in Gruul:

4 Decks
Game Trail
16 copies - 4 average
Cinder Glade
16 copies - 4 average
Hangarback Walker
12 copies - 3 average
Roast
11 copies - 2.75 average
Pia and Kiran Nalaar
9 copies - 2.25 average
Arlinn Kord
9 copies - 2.25 average
Nissa, Voice of Zendikar
9 copies - 2.25 average
Thunderbreak Regent
8 copies - 2 average
Atarka's Command
8 copies - 2 average
Thopter Engineer
8 copies - 2 average
Sylvan Advocate
8 copies - 2 average
Draconic Roar
7 copies - 1.75 average
Westvale Abbey
7 copies - 1.75 average
Duskwatch Recruiter
7 copies - 1.75 average
Clip Wings
5 copies - 1.25 average
Den Protector
5 copies - 1.25 average
Elvish Visionary
4 copies - 1 average
Blisterpod
4 copies - 1 average
Cryptolith Rite
4 copies - 1 average
Impact Tremors
4 copies - 1 average