Persistent Constrictor

At the beginning of each opponent's upkeep, they lose 1 life and you put a -1/-1 counter on up to one target creature they control.
Persist (When this creature dies, if it had no -1/-1 counters on it, return it to the battlefield under its owner's control with a -1/-1 counter on it.)

Takenuma, Abandoned Mire

{T}: Add {B}.
Channel — {3}{B}, Discard Takenuma, Abandoned Mire: Mill three cards, then return a creature or planeswalker card from your graveyard to your hand. This ability costs {1} less to activate for each legendary creature you control.

Read the Bones

Scry 2, then draw two cards. You lose 2 life. (To scry 2, look at the top two cards of your library, then put any number of them on the bottom and the rest on top in any order.)

Disfigure

Target creature gets -2/-2 until end of turn.

Jet Medallion

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

Withering Torment

Destroy target creature or enchantment. You lose 2 life.

Scuttlemutt

{T}: Add one mana of any color.
{T}: Target creature becomes the color or colors of your choice until end of turn.

Entomb

Search your library for a card, put that card into your graveyard, then shuffle.

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.

Tooth of Chiss-Goria

Flash
Affinity for artifacts (This spell costs {1} less to cast for each artifact you control.)
{T}: Target creature gets +1/+0 until end of turn.

Lose Hope

Target creature gets -1/-1 until end of turn. Scry 2. (Look at the top two cards of your library, then put any number of them on the bottom and the rest on top in any order.)

Sangromancer

Flying
Whenever a creature an opponent controls dies, you may gain 3 life.
Whenever an opponent discards a card, you may gain 3 life.

Horobi, Death's Wail

Flying
Whenever a creature becomes the target of a spell or ability, destroy that creature.

Songs of the Damned

Add {B} for each creature card in your graveyard.

Subtle Strike

Choose one or both —
• Target creature gets -1/-1 until end of turn.
• Put a +1/+1 counter on target creature.

Fate Unraveler

Whenever an opponent draws a card, Fate Unraveler deals 1 damage to that player.

Wail of the Nim

Choose one —
• Regenerate each creature you control.
• Wail of the Nim deals 1 damage to each creature and each player.
Entwine {B} (Choose both if you pay the entwine cost.)

Blood Pact

Target player draws two cards and loses 2 life.

Slice from the Shadows

This spell can't be countered. (This includes by the ward ability.)
Target creature gets -X/-X until end of turn.

Nighthaze

Target creature gains swampwalk until end of turn. (It can't be blocked as long as defending player controls a Swamp.)
Draw a card.

Squee's Toy

{T}: Prevent the next 1 damage that would be dealt to target creature this turn.

Swamp

Beacon of Unrest

Put target artifact or creature card from a graveyard onto the battlefield under your control. Shuffle Beacon of Unrest into its owner's library.

Nefashu

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

Virtus the Veiled

Partner with Gorm the Great (When this creature enters, target player may put Gorm into their hand from their library, then shuffle.)
Deathtouch
Whenever Virtus the Veiled deals combat damage to a player, that player loses half their life, rounded up.

Maze of Ith

{T}: Untap target attacking creature. Prevent all combat damage that would be dealt to and dealt by that creature this turn.

Vampiric Tutor

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

Sorceress Queen

{T}: Target creature other than Sorceress Queen has base power and toughness 0/2 until end of turn.

Tragic Slip

Target creature gets -1/-1 until end of turn.
Morbid — That creature gets -13/-13 until end of turn instead if a creature died this turn.

Cut Down

Destroy target creature with total power and toughness 5 or less.

Tetzimoc, Primal Death

Deathtouch
{B}, Reveal Tetzimoc, Primal Death from your hand: Put a prey counter on target creature. Activate only during your turn.
When Tetzimoc enters, destroy each creature your opponents control with a prey counter on it.

Imp's Mischief

Change the target of target spell with a single target. You lose life equal to that spell's mana value.

Dark Ritual

Defile

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

Retreat to Hagra

Landfall — Whenever a land you control enters, choose one —
• Target creature gets +1/+0 and gains deathtouch until end of turn.
• Each opponent loses 1 life and you gain 1 life.

Bladebrand

Target creature gains deathtouch until end of turn.
Draw a card.

Fraying Omnipotence

Each player loses half their life, then discards half the cards in their hand, then sacrifices half the creatures they control. Round up each time.

Animate Dead

Enchant creature card in a graveyard
When Animate Dead enters, if it's on the battlefield, it loses "enchant creature card in a graveyard" and gains "enchant creature put onto the battlefield with Animate Dead." Return enchanted creature card to the battlefield under your control and attach Animate Dead to it. When Animate Dead leaves the battlefield, that creature's controller sacrifices it.
Enchanted creature gets -1/-0.

Whisper of the Dross

Target creature gets -1/-1 until end of turn. Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Liquimetal Coating

{T}: Target permanent becomes an artifact in addition to its other types until end of turn.

Scale of Chiss-Goria

Flash
Affinity for artifacts (This spell costs {1} less to cast for each artifact you control.)
{T}: Target creature gets +0/+1 until end of turn.

Aphotic Wisps

Target creature becomes black and gains fear until end of turn. (It can't be blocked except by artifact creatures and/or black creatures.)
Draw a card.

Sol Ring

Orcish Bowmasters

Flash
When Orcish Bowmasters enters and whenever an opponent draws a card except the first one they draw in each of their draw steps, Orcish Bowmasters deals 1 damage to any target. Then amass Orcs 1.

Reanimate

Put target creature card from a graveyard onto the battlefield under your control. You lose life equal to its mana value.

Distorting Lens

{T}: Target permanent becomes the color of your choice until end of turn.

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.)

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.

Caustic Crawler

Landfall — Whenever a land you control enters, you may have target creature get -1/-1 until end of turn.

Bojuka Bog

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

Demonic Tutor

Search your library for a card, put that card into your hand, then shuffle.

Shadow Alley Denizen

Whenever another black creature you control enters, target creature gains intimidate until end of turn. (It can't be blocked except by artifact creatures and/or creatures that share a color with it.)

Glaring Spotlight

Creatures your opponents control with hexproof can be the targets of spells and abilities you control as though they didn't have hexproof.
{3}, Sacrifice Glaring Spotlight: Creatures you control gain hexproof until end of turn and can't be blocked this turn.

Shadowspear

Equipped creature gets +1/+1 and has trample and lifelink.
{1}: Permanents your opponents control lose hexproof and indestructible until end of turn.
Equip {2}

Liquimetal Torque

{T}: Add {C}.
{T}: Target nonland permanent becomes an artifact in addition to its other types until end of turn.

Solemn Simulacrum

When Solemn Simulacrum enters, you may search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.
When Solemn Simulacrum dies, you may draw a card.

Sepulchral Primordial

Intimidate (This creature can't be blocked except by artifact creatures and/or creatures that share a color with it.)
When Sepulchral Primordial enters, for each opponent, you may put up to one target creature card from that player's graveyard onto the battlefield under your control.

Drana, Kalastria Bloodchief

Flying
{X}{B}{B}: Target creature gets -0/-X until end of turn and Drana, Kalastria Bloodchief gets +X/+0 until end of turn.

Buried Alive

Search your library for up to three creature cards, put them into your graveyard, then shuffle.

Cauldron of Souls

{T}: Choose any number of target creatures. Each of those creatures gains persist until end of turn. (When it dies, if it had no -1/-1 counters on it, return it to the battlefield under its owner's control with a -1/-1 counter on it.)

Arcane Signet

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

Harvester of Souls

Deathtouch
Whenever another nontoken creature dies, you may draw a card.

Charcoal Diamond

Charcoal Diamond enters tapped.
{T}: Add {B}.

Underworld Dreams

Whenever an opponent draws a card, Underworld Dreams deals 1 damage to that player.

Zulaport Cutthroat

Whenever Zulaport Cutthroat or another creature you control dies, each opponent loses 1 life and you gain 1 life.

Peer into the Abyss

Target player draws cards equal to half the number of cards in their library and loses half their life. Round up each time.

Warlock Class

(Gain the next level as a sorcery to add its ability.)
At the beginning of your end step, if a creature died this turn, each opponent loses 1 life.
{1}{B}: Level 2
When this Class becomes level 2, look at the top three cards of your library. Put one of them into your hand and the rest into your graveyard.
{6}{B}: Level 3
At the beginning of your end step, each opponent loses life equal to the life they lost this turn. (Damage causes loss of life.)

Mogis's Marauder

When Mogis's Marauder enters, up to X target creatures each gain intimidate and haste until end of turn, where X is your devotion to black. (A creature with intimidate can't be blocked except by artifact creatures and/or creatures that share a color with it. Each {B} in the mana costs of permanents you control counts toward your devotion to black.)