Most played cards in Mono Black Control:

4 Decks
Consume Spirit
12 copies - 3 average
Chainer's Edict
12 copies - 3 average
Duress
12 copies - 3 average
Mutilate
11 copies - 2.75 average
10 copies - 2.5 average
Cabal Coffers
9 copies - 2.25 average
Cranial Extraction
8 copies - 2 average
Diabolic Tutor
7 copies - 1.75 average
Innocent Blood
7 copies - 1.75 average
Phyrexian Arena
6 copies - 1.5 average
Nantuko Shade
6 copies - 1.5 average
Corrupt
6 copies - 1.5 average
Kokusho, the Evening Star
5 copies - 1.25 average
Oblivion Stone
5 copies - 1.25 average
Cabal Therapy
4 copies - 1 average
Guardian Idol
4 copies - 1 average
Chrome Mox
4 copies - 1 average
Blinkmoth Nexus
4 copies - 1 average
Death Cloud
4 copies - 1 average
Terror
4 copies - 1 average