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.

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.

Not Dead After All

Until end of turn, target creature you control gains "When this creature dies, return it to the battlefield tapped under its owner's control, then create a Wicked Role token attached to it." (Enchanted creature gets +1/+1. When this Aura is put into a graveyard, each opponent loses 1 life.)

Breathe Your Last

Destroy target creature or planeswalker. You gain 1 life for each of its colors.

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.

Sol Ring

Blood Pet

Profane Transfusion

Two target players exchange life totals. You create an X/X colorless Horror artifact creature token, where X is the difference between those players' life totals.

Undying Malice

Until end of turn, target creature gains "When this creature dies, return it to the battlefield tapped under its owner's control with a +1/+1 counter on it."

Magus of the Mirror

{T}, Sacrifice Magus of the Mirror: Exchange life totals with target opponent. Activate only during your upkeep.

Exsanguinate

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

Diabolic Tutor

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

Toxic Deluge

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

Consuming Corruption

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

Maga, Traitor to Mortals

Maga, Traitor to Mortals enters with X +1/+1 counters on it.
When Maga enters, target player loses life equal to the number of +1/+1 counters on it.

Arcane Signet

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

Mutilate

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

Defile

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

Charcoal Diamond

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

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.

Platinum Angel

Flying
You can't lose the game and your opponents can't win the game.

Sign in Blood

Target player draws two cards and loses 2 life.

Blood Celebrant

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

Imp's Mischief

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

Helm of Awakening

Greed

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.)

Repay in Kind

Each player's life total becomes the lowest life total among all players.

Feed the Swarm

Destroy target creature or enchantment an opponent controls. You lose life equal to that permanent's mana value.

Basilica Screecher

Flying
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.)

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.

Thought Vessel

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

Phage the Untouchable

When Phage the Untouchable enters, if you didn't cast it from your hand, you lose the game.
Whenever Phage deals combat damage to a creature, destroy that creature. It can't be regenerated.
Whenever Phage deals combat damage to a player, that player loses the game.

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.)

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.

Jet Medallion

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

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.