Plaguecrafter

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

Cabal Executioner

Whenever this creature deals combat damage to a player, that player sacrifices a creature of their choice.
Morph {3}{B}{B} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)

Blood Seeker

Whenever a creature an opponent controls enters, you may have that player lose 1 life.

Fate Unraveler

Whenever an opponent draws a card, this creature deals 1 damage to that player.

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.

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 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.)

Indulgent Tormentor

Flying
At the beginning of your upkeep, draw a card unless target opponent sacrifices a creature of their choice or pays 3 life.

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}.

Massacre Wurm

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

Rankle, Master of Pranks

Flying, haste
Whenever Rankle deals combat damage to a player, choose any number —
• Each player discards a card.
• Each player loses 1 life and draws a card.
• Each player sacrifices a creature of their choice.

Underworld Dreams

Whenever an opponent draws a card, this enchantment deals 1 damage to that player.

Dark Ritual

Price of Knowledge

Players have no maximum hand size.
At the beginning of each opponent's upkeep, this enchantment deals damage to that player equal to the number of cards in that player's hand.

Ob Nixilis, the Hate-Twisted

Whenever an opponent draws a card, Ob Nixilis deals 1 damage to that player.
−2: Destroy target creature. Its controller draws two cards.

Exsanguinate

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

Bloodgift Demon

Flying
At the beginning of your upkeep, target player draws a card and loses 1 life.

Painful Quandary

Whenever an opponent casts a spell, that player loses 5 life unless they discard a card.

Gray Merchant of Asphodel

When this creature 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.)

Seizan, Perverter of Truth

At the beginning of each player's upkeep, that player loses 2 life and draws two cards.

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.

Archfiend of Depravity

Flying
At the beginning of each opponent's end step, that player chooses up to two creatures they control, then sacrifices the rest.

Sol Ring

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.

Gixian Puppeteer

Whenever you draw your second card each turn, each opponent loses 2 life and you gain 2 life.
When this creature dies, return another target creature card with mana value 3 or less from your graveyard to the battlefield.

Ob Nixilis of the Black Oath

+2: Each opponent loses 1 life. You gain life equal to the life lost this way.
−2: Create a 5/5 black Demon creature token with flying. You lose 2 life.
−8: You get an emblem with "{1}{B}, Sacrifice a creature: You gain X life and draw X cards, where X is the sacrificed creature's power."
Ob Nixilis of the Black Oath can be your commander.

Polluted Bonds

Whenever a land an opponent controls enters, that player loses 2 life and you gain 2 life.

Baleful Mastery

You may pay {1}{B} rather than pay this spell's mana cost.
If the {1}{B} cost was paid, an opponent draws a card.
Exile target creature or planeswalker.

Starving Revenant

When this creature enters, surveil 2. Then for each card you put on top of your library, you draw a card and you lose 3 life.
Descend 8 — Whenever you draw a card, if there are eight or more permanent cards in your graveyard, target opponent loses 1 life and you gain 1 life.