Most played cards in Mono Black Aggro:

4 Decks
Cabal Therapy
16 copies - 4 average
Duress
16 copies - 4 average
Withered Wretch
16 copies - 4 average
Dark Confidant
15 copies - 3.75 average
Chainer's Edict
13 copies - 3.25 average
Rotlung Reanimator
12 copies - 3 average
Smother
11 copies - 2.75 average
Chrome Mox
11 copies - 2.75 average
Recoil
8 copies - 2 average
Polluted Delta
8 copies - 2 average
Darkblast
8 copies - 2 average
Braids, Cabal Minion
8 copies - 2 average
Blinkmoth Nexus
7 copies - 1.75 average
7 copies - 1.75 average
Ravenous Rats
6 copies - 1.5 average
Umezawa's Jitte
6 copies - 1.5 average
Chittering Rats
6 copies - 1.5 average
Engineered Plague
6 copies - 1.5 average
Graveborn Muse
4 copies - 1 average
Mesmeric Fiend
4 copies - 1 average