Pontiff of Blight

Extort (Whenever you cast a spell, you may pay {W/B}. If you do, each opponent loses 1 life and you gain that much life.)
Other creatures you control have extort. (If a creature has multiple instances of extort, each triggers separately.)

Font of Agonies

Whenever you pay life, put that many blood counters on Font of Agonies.
{1}{B}, Remove four blood counters from Font of Agonies: Destroy target creature.

Ad Nauseam

Reveal the top card of your library and put that card into your hand. You lose life equal to its mana value. You may repeat this process any number of times.

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.

Exquisite Blood

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

Thran Dynamo

Cabal Ritual

Add {B}{B}{B}.
Threshold — Add {B}{B}{B}{B}{B} instead if seven or more cards are in your graveyard.

Culling the Weak

As an additional cost to cast this spell, sacrifice a creature.
Add {B}{B}{B}{B}.

Gifted Aetherborn

Street Wraith

Swampwalk (This creature can't be blocked as long as defending player controls a Swamp.)
Cycling—Pay 2 life. (Pay 2 life, Discard this card: Draw a card.)

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.

Blood Pet

Diamond Mare

As Diamond Mare enters, choose a color.
Whenever you cast a spell of the chosen color, you gain 1 life.

Ravenous Chupacabra

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

Gravecrawler

Gravecrawler can't block.
You may cast Gravecrawler from your graveyard as long as you control a Zombie.

Dread Shade

{B}: Dread Shade gets +1/+1 until end of turn.

Greed

Sign in Blood

Target player draws two cards and loses 2 life.

Sol Ring

Thrull Parasite

Extort (Whenever you cast a spell, you may pay {W/B}. If you do, each opponent loses 1 life and you gain that much life.)
{T}, Pay 2 life: Remove a counter from target nonland permanent.

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.)

Defile

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

Infernal Contract

Draw four cards. You lose half your life, rounded up.

Price of Fame

This spell costs {2} less to cast if it targets a legendary creature.
Destroy target creature.
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.)

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.)

Swamp

Dark Ritual

Demon's Horn

Whenever a player casts a black spell, you may gain 1 life.

Arcane Signet

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

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.

Swiftfoot Boots

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

Magus of the Coffers

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

Lightning Greaves

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

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.

Mutilate

All creatures get -1/-1 until end of turn for each Swamp you control.

K'rrik, Son of Yawgmoth

({B/P} can be paid with either {B} or 2 life.)
Lifelink
For each {B} in a cost, you may pay 2 life rather than pay that mana.
Whenever you cast a black spell, put a +1/+1 counter on K'rrik, Son of Yawgmoth.

Blood Celebrant

{B}, Pay 1 life: Add one mana of any color.

Black Sun's Zenith

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

Staff of the Death Magus

Whenever you cast a black spell or a Swamp you control enters, you gain 1 life.

Ob Nixilis Reignited

+1: You draw a card and you lose 1 life.
−3: Destroy target creature.
−8: Target opponent gets an emblem with "Whenever a player draws a card, you lose 2 life."

Languish

All creatures get -4/-4 until end of turn.

Mind Stone

{T}: Add {C}.
{1}, {T}, Sacrifice Mind Stone: Draw a card.

Phyrexian Arena

At the beginning of your upkeep, you draw a card and you lose 1 life.

Dance of the Dead

Enchant creature card in a graveyard
When Dance of the 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 Dance of the Dead." Put enchanted creature card onto the battlefield tapped under your control and attach Dance of the Dead to it. When Dance of the Dead leaves the battlefield, that creature's controller sacrifices it.
Enchanted creature gets +1/+1 and doesn't untap during its controller's untap step.
At the beginning of the upkeep of enchanted creature's controller, that player may pay {1}{B}. If the player does, untap that creature.

Necropotence

Skip your draw step.
Whenever you discard a card, exile that card from your graveyard.
Pay 1 life: Exile the top card of your library face down. Put that card into your hand at the beginning of your next end step.

Zulaport Cutthroat

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

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.

Dread Presence

Whenever a Swamp you control enters, choose one —
• You draw a card and you lose 1 life.
• Dread Presence deals 2 damage to any target and you gain 2 life.

Plaguecrafter

When Plaguecrafter enters, each player sacrifices a creature or planeswalker of their choice. Each player who can't discards a card.

Fleshbag Marauder

When Fleshbag Marauder enters, each player sacrifices a creature of their choice.

Carrion Feeder

Carrion Feeder can't block.
Sacrifice a creature: Put a +1/+1 counter on Carrion Feeder.

Cabal Coffers

Expedition Map

{2}, {T}, Sacrifice Expedition Map: Search your library for a land card, reveal it, put it into your hand, then shuffle.

Cabal Stronghold

{T}: Add {C}.
{3}, {T}: Add {B} for each basic Swamp you control.

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.)

Gonti, Lord of Luxury

Deathtouch
When Gonti, Lord of Luxury enters, look at the top four cards of target opponent's library, exile one of them face down, then put the rest on the bottom of that library in a random order. You may cast that card for as long as it remains exiled, and mana of any type can be spent to cast that spell.

Hero's Downfall

Midnight Reaper

Whenever a nontoken creature you control dies, Midnight Reaper deals 1 damage to you and you draw a card.

Viscera Seer

Sacrifice a creature: Scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Bolas's Citadel

You may look at the top card of your library any time.
You may play lands and cast spells from the top of your library. If you cast a spell this way, pay life equal to its mana value rather than pay its mana cost.
{T}, Sacrifice ten nonland permanents: Each opponent loses 10 life.

Go for the Throat

Crypt Ghast

Extort (Whenever you cast a spell, you may pay {W/B}. If you do, each opponent loses 1 life and you gain that much life.)
Whenever you tap a Swamp for mana, add an additional {B}.

Nightmare Unmaking

Choose one —
• Exile each creature with power greater than the number of cards in your hand.
• Exile each creature with power less than the number of cards in your hand.

Reiver Demon

Flying
When Reiver Demon enters, if you cast it from your hand, destroy all nonartifact, nonblack creatures. They can't be regenerated.

Exsanguinate

Each opponent loses X life. You gain life equal to the life lost this way.

Night's Whisper

Force of Despair

If it's not your turn, you may exile a black card from your hand rather than pay this spell's mana cost.
Destroy all creatures that entered this turn.

Tendrils of Corruption

Tendrils of Corruption deals X damage to target creature and you gain X life, where X is the number of Swamps you control.

Vampiric Link

Enchant creature
Whenever enchanted creature deals damage, you gain that much life.

Dark Confidant

At the beginning of your upkeep, reveal the top card of your library and put that card into your hand. You lose life equal to its mana value.