Most played cards in Black Market:

1 Decks
Liliana of the Veil
4 copies - 4 average
Mutilate
4 copies - 4 average
Phyrexian Metamorph
3 copies - 3 average
Pristine Talisman
3 copies - 3 average
Ichor Wellspring
3 copies - 3 average
Nihil Spellbomb
3 copies - 3 average
Tezzeret, Agent of Bolas
3 copies - 3 average
Solemn Simulacrum
3 copies - 3 average
Black Sun's Zenith
2 copies - 2 average
Barter in Blood
2 copies - 2 average
Dismember
2 copies - 2 average
Spellskite
2 copies - 2 average
Karn Liberated
2 copies - 2 average
Duress
2 copies - 2 average
Inkmoth Nexus
2 copies - 2 average
Ghost Quarter
2 copies - 2 average
Mycosynth Wellspring
2 copies - 2 average
Curse of Death's Hold
2 copies - 2 average
Doom Blade
2 copies - 2 average
Go for the Throat
2 copies - 2 average