Incremental Blight

Put a -1/-1 counter on target creature, two -1/-1 counters on another target creature, and three -1/-1 counters on a third target creature.

Nefashu

Whenever Nefashu attacks, up to five target creatures each get -1/-1 until end of turn.

Morbid Opportunist

Whenever one or more other creatures die, draw a card. This ability triggers only once each turn.

Bontu's Monument

Black creature spells you cast cost {1} less to cast.
Whenever you cast a creature spell, each opponent loses 1 life and you gain 1 life.

Swamp

Skinrender

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

Massacre Wurm

When Massacre Wurm enters, creatures your opponents control get -2/-2 until end of turn.
Whenever a creature an opponent controls dies, that player loses 2 life.

Harbinger of Night

At the beginning of your upkeep, put a -1/-1 counter on each creature.

Massacre Girl

Menace
When Massacre Girl enters, each other creature gets -1/-1 until end of turn. Whenever a creature dies this turn, each creature other than Massacre Girl gets -1/-1 until end of turn.

Instill Infection

Put a -1/-1 counter on target creature.
Draw a card.

Bojuka Bog

Bojuka Bog enters tapped.
When Bojuka Bog enters, exile target player's graveyard.
{T}: Add {B}.

Cower in Fear

Creatures your opponents control get -1/-1 until end of turn.

Lightning Greaves

Equipped creature has haste and shroud. (It can't be the target of spells or abilities.)
Equip {0}

Myriad Landscape

Myriad Landscape enters tapped.
{T}: Add {C}.
{2}, {T}, Sacrifice Myriad Landscape: Search your library for up to two basic land cards that share a land type, put them onto the battlefield tapped, then shuffle.

Festering Mummy

When Festering Mummy dies, you may put a -1/-1 counter on target creature.

Kaervek, the Spiteful

Dark Ritual

Contagion Clasp

When Contagion Clasp enters, put a -1/-1 counter on target creature.
{4}, {T}: Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Toxic Deluge

As an additional cost to cast this spell, pay X life.
All creatures get -X/-X until end of turn.

Festergloom

Nonblack creatures get -1/-1 until end of turn.

Drivnod, Carnage Dominus

If a creature dying causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.
{B/P}{B/P}, Exile three creature cards from your graveyard: Put an indestructible counter on Drivnod, Carnage Dominus. ({B/P} can be paid with either {B} or 2 life.)

Sanguine Bond

Whenever you gain life, target opponent loses that much life.

Fevered Convulsions

{2}{B}{B}: Put a -1/-1 counter on target creature.

Fume Spitter

Sacrifice Fume Spitter: Put a -1/-1 counter on target creature.

Liliana's Influence

Put a -1/-1 counter on each creature you don't control. You may search your library and/or graveyard for a card named Liliana, Death Wielder, reveal it, and put it into your hand. If you search your library this way, shuffle.

Swiftfoot Boots

Equipped creature has hexproof and haste. (It can't be the target of spells or abilities your opponents control.)
Equip {1}

Cabal Coffers

{2}, {T}: Add {B} for each Swamp you control.

Maha, Its Feathers Night

Flying, trample
Ward—Discard a card.
Creatures your opponents control have base toughness 1.

Hunted Bonebrute

Menace
When Hunted Bonebrute enters, target opponent creates two 1/1 white Dog creature tokens.
When Hunted Bonebrute dies, each opponent loses 3 life.
Disguise {1}{B}

Weed-Pruner Poplar

At the beginning of your upkeep, target creature other than Weed-Pruner Poplar gets -1/-1 until end of turn.

Midnight Banshee

Wither (This deals damage to creatures in the form of -1/-1 counters.)
At the beginning of your upkeep, put a -1/-1 counter on each nonblack creature.

Splendid Agony

Distribute two -1/-1 counters among one or two target creatures.

Exquisite Blood

Whenever an opponent loses life, you gain that much life.

Night of Souls' Betrayal

Soul Snuffers

When Soul Snuffers enters, put a -1/-1 counter on each creature.

Plague Mare

Plague Mare can't be blocked by white creatures.
When Plague Mare enters, creatures your opponents control get -1/-1 until end of turn.

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.

Neutralize the Guards

Creatures target opponent controls get -1/-1 until end of turn. Surveil 2. (Look at the top two cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)

Arcane Signet

{T}: Add one mana of any color in your commander's color identity.

Carnifex Demon

Flying
Carnifex Demon enters with two -1/-1 counters on it.
{B}, Remove a -1/-1 counter from Carnifex Demon: Put a -1/-1 counter on each other creature.

Massacre Girl, Known Killer

Menace
Creatures you control have wither. (They deal damage to creatures in the form of -1/-1 counters.)
Whenever a creature an opponent controls dies, if its toughness was less than 1, draw a card.

Sol Ring

Vilis, Broker of Blood

Flying
{B}, Pay 2 life: Target creature gets -1/-1 until end of turn.
Whenever you lose life, draw that many cards. (Damage causes loss of life.)

Nest of Scarabs

Whenever you put one or more -1/-1 counters on a creature, create that many 1/1 black Insect creature tokens.

Corrosive Mentor

Black creatures you control have wither. (They deal damage to creatures in the form of -1/-1 counters.)

Reliquary Tower

You have no maximum hand size.
{T}: Add {C}.

Blowfly Infestation

Whenever a creature dies, if it had a -1/-1 counter on it, put a -1/-1 counter on target creature.

Vampiric Tutor

Search your library for a card, then shuffle and put that card on top. You lose 2 life.

Black Sun's Zenith

Put X -1/-1 counters on each creature. Shuffle Black Sun's Zenith into its owner's library.

Deathgreeter

Whenever another creature dies, you may gain 1 life.

Jet Medallion

Black spells you cast cost {1} less to cast.

Smoldering Butcher

Wither (This deals damage to creatures in the form of -1/-1 counters.)

Blood Artist

Whenever Blood Artist or another creature dies, target player loses 1 life and you gain 1 life.

Make Obsolete

Spitting Dilophosaurus

Whenever Spitting Dilophosaurus enters or attacks, put a -1/-1 counter on up to one target creature.
Creatures your opponents control with -1/-1 counters on them can't block.

Curse of Death's Hold

Enchant player
Creatures enchanted player controls get -1/-1.

Yawgmoth, Thran Physician

Protection from Humans
Pay 1 life, Sacrifice another creature: Put a -1/-1 counter on up to one target creature and draw a card.
{B}{B}, Discard a card: Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Shrivel

All creatures get -1/-1 until end of turn.

Gruesome Realization

Choose one —
• You draw two cards and you lose 2 life.
• Creatures your opponents control get -1/-1 until end of turn.

Gisa, Glorious Resurrector

If a creature an opponent controls would die, exile it instead.
At the beginning of your upkeep, put all creature cards exiled with Gisa, Glorious Resurrector onto the battlefield under your control. They gain decayed. (A creature with decayed can't block. When it attacks, sacrifice it at end of combat.)

Liliana, Death Wielder

+2: Put a -1/-1 counter on up to one target creature.
−3: Destroy target creature with a -1/-1 counter on it.
−10: Return all creature cards from your graveyard to the battlefield.

Nausea

Defile

Target creature gets -1/-1 until end of turn for each Swamp you control.

Pestilence

At the beginning of the end step, if no creatures are on the battlefield, sacrifice Pestilence.
{B}: Pestilence deals 1 damage to each creature and each player.

Black Market

Whenever a creature dies, put a charge counter on Black Market.
At the beginning of your first main phase, add {B} for each charge counter on Black Market.

Necroskitter

Wither (This deals damage to creatures in the form of -1/-1 counters.)
Whenever a creature an opponent controls with a -1/-1 counter on it dies, you may return that card to the battlefield under your control.

Syr Konrad, the Grim

Whenever another creature dies, or a creature card is put into a graveyard from anywhere other than the battlefield, or a creature card leaves your graveyard, Syr Konrad, the Grim deals 1 damage to each opponent.
{1}{B}: Each player mills a card. (They each put the top card of their library into their graveyard.)

Grim Physician

When Grim Physician dies, target creature an opponent controls gets -1/-1 until end of turn.

Banewhip Punisher

When Banewhip Punisher enters, you may put a -1/-1 counter on target creature.
{B}, Sacrifice Banewhip Punisher: Destroy target creature that has a -1/-1 counter on it.