A Mono-Black Control deck with a focus on Extort.
Thrull Parasite
is the go-to Extort card for its low cost, it also helps against Planeswalkers and +1/+1 counters.
Basilica Screecher
provides Extort and is a flyer.
Blood Scrivener
allows you to refill your hand faster should you empty it and provides decent Tempo.
Thoughtseize and Lifebane Zombie allow you to scout out potential threats your opponent may have planned for you and remove them. Lifebane Zombie also provides a heavy hitting attacker with evasion should your opponent not have any Black or Artifact creatures.
Liliana's Reaver
is an extremely powerful card providing powerful control on both the offensive and the defensive.
Crypt Ghast provides Extort and speeds up your mana base to insane amounts letting you cast high cost cards early and/or Extort for insane amounts.
Whip of Erebos gives Lifelink to all of your creatures, allowing you to control for longer and stall out the game until you can drop a bomb or whittle your opponent's life away. It also synergizes well with ETB creatures such as Lifebane Zombie, Gray Merchant of Asphodel, or Abhorrent Overlord should any of them be in your graveyard.
Erebos, God of the Dead is an insane card, allowing you to shut down Lifegain strategies, providing insane card advantage allowing you to play more spells and Extort more with your insane mana base. And should you meet his Devotion he becomes a powerful, Indestructible creature both on the Offensive and the Defensive.
Gray Merchant of Asphodel is a strong bomb that can turn a battle, if not finish it. Given its remotely high casting cost and requires set-up, only a singleton is in the deck.
Pontiff of Blight makes late game a horror for your opponent, allowing you to get tons of Extort triggers. It also has high toughness allowing you to block strong attackers.
Abhorrent Overlord is a huge powerhouse card. With high Devotion you can easily win within the next few turns if it doesn't already make your opponent scoop. Should you get it out with not so high Devotion, it still is a force to be reckoned with. This card alone won me at least 3 matches during Pre-release where I went 3-1.
Read the Bones allows you filter your cards and provides card advantage.
Stab Wound
controls your opponent's larger creatures and also in turn hurts them.
Hero's Downfall gets rid of any creature or Planeswalker threats your opponent may have.
Sideboard:
Cremate
is side boarded for decks that gain advantage through the Graveyard (mainly decks with Golgari colors in them) and thins out your deck for a low cost.
Erebos, God of the Dead is side boarded for decks that rely heavily on Lifegain.
Glaring Spotlight
is side boarded for Bant Hexproof Auras.
Hythonia the Cruel
is side boarded for decks that swarm the field (such as Selesnya tokens, Boros aggro, and decks running
Master of Waves
and/or Young Pyromancer).
Nightveil Specter is side boarded to replace Lifebane Zombie should I be up against a Black deck that is also not running Green or White.
Viper's Kiss
is side boarded for decks that revolve around activated abilities (such as monstrosity) or rely on low toughness Creatures (such as
Master of Waves
or White Weenie decks).