Most played cards in B/G Aggro:

3 Decks
Dark Confidant
12 copies - 4 average
Mutavault
12 copies - 4 average
Tarmogoyf
12 copies - 4 average
Smallpox
12 copies - 4 average
Treetop Village
12 copies - 4 average
Augur of Skulls
12 copies - 4 average
Putrefy
12 copies - 4 average
Extirpate
11 copies - 3.67 average
Thoughtseize
11 copies - 3.67 average
Overgrown Tomb
11 copies - 3.67 average
Umezawa's Jitte
10 copies - 3.33 average
Bloodstained Mire
9 copies - 3 average
Nyxathid
9 copies - 3 average
Cry of Contrition
8 copies - 2.67 average
The Rack
8 copies - 2.67 average
Bitterblossom
8 copies - 2.67 average
Darkblast
7 copies - 2.33 average
Chrome Mox
6 copies - 2 average
Damnation
6 copies - 2 average
Stupor
6 copies - 2 average