LANDS (26):
4x Field of Ruin
3x Cabal Stronghold
19x Swamp
SPELLS (34):
4x Divest (B)
4x Duress (B)
4x Sovereign's Bite (1B)
4x Murder (1BB)
4x Dread Shade (BBB)
3x Ritual of Soot (2BB)
3x Mastermind's Acquisition (2BB)
2x Primal Amulet (4)
2x Liliana's Contract (3BB)
1x The Immortal Sun (6)
There's some good ramp, but there's no scaling black spells to sink all that mana into.
The gameplan here is to bleed them dry and build up your mana, then just beat them to death with an ever growing Shade after they're defenseless.
Sovereign's Bite can double up when Primal Amulet is out to help finish things off or to buy some time.
Just let them play creatures, wipe them all out on turn 4, then pick off whatever comes next with Murder, etc.
Liliana's Contract gives us some actual card draw; the demon part is unnecessary.
The Immortal Sun wins the game if it hits the table, and with the tutor of Mastermind's Acquisition I can fetch that out or other spells.