Gray Merchant of Asphodel

When Gray Merchant of Asphodel enters, each opponent loses X life, where X is your devotion to black. You gain life equal to the life lost this way. (Each {B} in the mana costs of permanents you control counts toward your devotion to black.)

Vampire Nighthawk

Flying
Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)
Lifelink (Damage dealt by this creature also causes you to gain that much life.)

Ruthless Cullblade

Ruthless Cullblade gets +2/+1 as long as an opponent has 10 or less life.

Dusk Legion Zealot

When Dusk Legion Zealot enters, you draw a card and you lose 1 life.

Pestilence Demon

Flying
{B}: Pestilence Demon deals 1 damage to each creature and each player.

Morbid Plunder

Return up to two target creature cards from your graveyard to your hand.

Snuff Out

If you control a Swamp, you may pay 4 life rather than pay this spell's mana cost.
Destroy target nonblack creature. It can't be regenerated.

Mind Rot

Revenant

Flying
Revenant's power and toughness are each equal to the number of creature cards in your graveyard.

Cruel Edict

Target opponent sacrifices a creature of their choice.

Sign in Blood

Target player draws two cards and loses 2 life.

Doom Blade

Mortivore

Mortivore's power and toughness are each equal to the number of creature cards in all graveyards.
{B}: Regenerate Mortivore. (The next time this creature would be destroyed this turn, instead tap it, remove it from combat, and heal all damage on it.)

Swamp

Scavenger Drake

Flying
Whenever another creature dies, you may put a +1/+1 counter on Scavenger Drake.

Nightmare

Flying (This creature can't be blocked except by creatures with flying or reach.)
Nightmare's power and toughness are each equal to the number of Swamps you control.

Ogre Slumlord

Whenever another nontoken creature dies, you may create a 1/1 black Rat creature token.
Rats you control have deathtouch.

Typhoid Rats

Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)

Terror

Destroy target nonartifact, nonblack creature. It can't be regenerated.

Skinrender

When Skinrender enters, put three -1/-1 counters on target creature.

Ravenous Chupacabra

When Ravenous Chupacabra enters, destroy target creature an opponent controls.

Phyrexian Rager

When Phyrexian Rager enters, you draw a card and you lose 1 life.

Cadaver Imp

Flying
When Cadaver Imp enters, you may return target creature card from your graveyard to your hand.

Ravenous Rats

When Ravenous Rats enters, target opponent discards a card.

Geth's Verdict

Target player sacrifices a creature of their choice and loses 1 life.

Tortured Existence

{B}, Discard a creature card: Return target creature card from your graveyard to your hand.

Rise from the Grave

Put target creature card from a graveyard onto the battlefield under your control. That creature is a black Zombie in addition to its other colors and types.

Ostracize

Target opponent reveals their hand. You choose a creature card from it. That player discards that card.

Ashling, the Extinguisher

Whenever Ashling, the Extinguisher deals combat damage to a player, choose target creature that player controls. The player sacrifices that creature.

Gatekeeper of Malakir

Kicker {B} (You may pay an additional {B} as you cast this spell.)
When this creature enters, if it was kicked, target player sacrifices a creature of their choice.

Unburden

Target player discards two cards.
Cycling {2} ({2}, Discard this card: Draw a card.)

Ascendant Evincar

Flying (This creature can't be blocked except by creatures with flying or reach.)
Other black creatures get +1/+1.
Nonblack creatures get -1/-1.