Most played cards in Mono Black Aggro:

5 Decks
Hypnotic Specter
18 copies - 3.6 average
Phyrexian Arena
13 copies - 2.6 average
Ravenous Rats
12 copies - 2.4 average
Hand of Cruelty
12 copies - 2.4 average
Cranial Extraction
11 copies - 2.2 average
Quicksand
11 copies - 2.2 average
Nekrataal
11 copies - 2.2 average
Sickening Shoal
10 copies - 2 average
9 copies - 1.8 average
Consume Spirit
9 copies - 1.8 average
Umezawa's Jitte
8 copies - 1.6 average
Nezumi Shortfang
8 copies - 1.6 average
Last Gasp
8 copies - 1.6 average
Eradicate
8 copies - 1.6 average
Cruel Edict
8 copies - 1.6 average
Blackmail
8 copies - 1.6 average
Ink-Eyes, Servant of Oni
7 copies - 1.4 average
Hideous Laughter
6 copies - 1.2 average
Kagemaro, First to Suffer
5 copies - 1 average
Unholy Strength
4 copies - 0.8 average