Most played cards in B/G Aggro:

2 Decks
Tendrils of Corruption
8 copies - 4 average
Damnation
7 copies - 3.5 average
Slaughter Pact
5 copies - 2.5 average
Urborg, Tomb of Yawgmoth
5 copies - 2.5 average
Riftsweeper
4 copies - 2 average
Korlash, Heir to Blackblade
4 copies - 2 average
Call of the Herd
4 copies - 2 average
Horizon Canopy
4 copies - 2 average
Scryb Ranger
4 copies - 2 average
Search for Tomorrow
4 copies - 2 average
Krosan Grip
4 copies - 2 average
Extirpate
4 copies - 2 average
Sudden Death
4 copies - 2 average
Spectral Force
4 copies - 2 average
Augur of Skulls
4 copies - 2 average
Psychotic Episode
4 copies - 2 average
Stupor
4 copies - 2 average
Flagstones of Trokair
4 copies - 2 average
Tarmogoyf
4 copies - 2 average
Chromatic Star
4 copies - 2 average