Most played cards in Mono Black Control:

2 Decks
Demigod of Revenge
8 copies - 4 average
Fulminator Mage
8 copies - 4 average
Infest
6 copies - 3 average
Caves of Koilos
4 copies - 2 average
Underworld Dreams
4 copies - 2 average
4 copies - 2 average
Tidehollow Sculler
4 copies - 2 average
Fetid Heath
4 copies - 2 average
Profane Command
4 copies - 2 average
Stillmoon Cavalier
4 copies - 2 average
Thoughtseize
4 copies - 2 average
Nyxathid
4 copies - 2 average
Path to Exile
4 copies - 2 average
Terror
4 copies - 2 average
Corrupt
4 copies - 2 average
Leechridden Swamp
4 copies - 2 average
Shriekmaw
4 copies - 2 average
Mutavault
4 copies - 2 average
Burrenton Forge-Tender
4 copies - 2 average
Graveborn Muse
3 copies - 1.5 average