Altar of Dementia

Sacrifice a creature: Target player mills cards equal to the sacrificed creature's power.

Swamp

Gix's Command

Choose two —
• Put two +1/+1 counters on up to one creature. It gains lifelink until end of turn.
• Destroy each creature with power 2 or less.
• Return up to two creature cards from your graveyard to your hand.
• Each opponent sacrifices a creature with the highest power among creatures they control.

Gix, Yawgmoth Praetor

Whenever a creature deals combat damage to one of your opponents, its controller may pay 1 life. If they do, they draw a card.
{4}{B}{B}{B}, Discard X cards: Exile the top X cards of target opponent's library. You may play lands and cast spells from among cards exiled this way without paying their mana costs.

Dark Ritual

Ashnod's Altar

Elder Brain

Menace
Whenever Elder Brain attacks a player, exile all cards from that player's hand, then they draw that many cards. You may play lands and cast spells from among the exiled cards for as long as they remain exiled. If you cast a spell this way, you may spend mana as though it were mana of any color to cast it.

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.)

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.

Commander's Sphere

{T}: Add one mana of any color in your commander's color identity.
Sacrifice Commander's Sphere: Draw a card.

Abnormal Endurance

Until end of turn, target creature gets +2/+0 and gains "When this creature dies, return it to the battlefield tapped under its owner's control."

Altar's Reap

As an additional cost to cast this spell, sacrifice a creature.
Draw two cards.

Tevesh Szat, Doom of Fools

+2: Create two 0/1 black Thrull creature tokens.
+1: You may sacrifice another creature or planeswalker. If you do, draw two cards, then draw another card if the sacrificed permanent was a commander.
−10: Gain control of all commanders. Put all commanders from the command zone onto the battlefield under your control.
Tevesh Szat, Doom of Fools can be your commander.
Partner

Arcane Signet

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

Culling the Weak

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

Village Rites

Skull Collector

At the beginning of your upkeep, return a black creature you control to its owner's hand.
{1}{B}: Regenerate Skull Collector.

Sidisi, Undead Vizier

Deathtouch
Exploit (When this creature enters, you may sacrifice a creature.)
When Sidisi, Undead Vizier exploits a creature, you may search your library for a card, put it into your hand, then shuffle.

Damnation

Destroy all creatures. They can't be regenerated.

Defile

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

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."

Phyrexian Altar

Sacrifice a creature: Add one mana of any color.

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.)

Defiler of Flesh

Menace
As an additional cost to cast black permanent spells, you may pay 2 life. Those spells cost {B} less to cast if you paid life this way. This effect reduces only the amount of black mana you pay.
Whenever you cast a black permanent spell, target creature you control gets +1/+1 and gains menace until end of turn.

Costly Plunder

As an additional cost to cast this spell, sacrifice an artifact or creature.
Draw two cards.

Supernatural Stamina

Bubbling Muck

Until end of turn, whenever a player taps a Swamp for mana, that player adds an additional {B}.

Return to Action

Until end of turn, target creature gets +1/+0 and gains lifelink and "When this creature dies, return it to the battlefield tapped under its owner's control."

Undying Evil

Target creature gains undying 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.)

Charcoal Diamond

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

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.

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.

Feed the Swarm

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

Vampiric Tutor

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

Nykthos, Shrine to Nyx

{T}: Add {C}.
{2}, {T}: Choose a color. Add an amount of mana of that color equal to your devotion to that color. (Your devotion to a color is the number of mana symbols of that color in the mana costs of permanents you control.)

Viscera Seer

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

Soldevi Adnate

{T}, Sacrifice a black or artifact creature: Add an amount of {B} equal to the sacrificed creature's mana value.

Caged Sun

As Caged Sun enters, choose a color.
Creatures you control of the chosen color get +1/+1.
Whenever a land's ability causes you to add one or more mana of the chosen color, add one additional mana of that color.

Strionic Resonator

{2}, {T}: Copy target triggered ability you control. You may choose new targets for the copy. (A triggered ability uses the words "when," "whenever," or "at.")

Mind Stone

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

Sword of the Animist

Equipped creature gets +1/+1.
Whenever equipped creature attacks, you may search your library for a basic land card, put it onto the battlefield tapped, then shuffle.
Equip {2}

Mutilate

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

Thought Vessel

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

Malakir Mire

Malakir Mire enters tapped.
{T}: Add {B}.

Malakir Rebirth

Choose target creature. You lose 2 life. Until end of turn, that creature gains "When this creature dies, return it to the battlefield tapped under its owner's control."

Malakir Rebirth // Malakir Mire

Hostile Negotiations

Exile the top three cards of your library in a face-down pile, then exile the top three cards of your library in another face-down pile. Look at the cards in each pile, then turn a pile of your choice face up. An opponent chooses one of those piles. Put that pile into your hand and the other into your graveyard. You lose 3 life.

Sceptre of Eternal Glory

{T}: Add one mana of any color.
{T}: Add three mana of any one color. Activate only if you control three or more lands with the same name.

Sol Ring

Sign in Blood

Target player draws two cards and loses 2 life.

Panharmonicon

If an artifact or creature entering causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.

Fake Your Own Death

Until end of turn, target creature gets +2/+0 and gains "When this creature dies, return it to the battlefield tapped under its owner's control and you create a Treasure token." (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Dauthi Voidwalker

Shadow (This creature can block or be blocked by only creatures with shadow.)
If a card would be put into an opponent's graveyard from anywhere, instead exile it with a void counter on it.
{T}, Sacrifice Dauthi Voidwalker: Choose an exiled card an opponent owns with a void counter on it. You may play it this turn without paying its mana cost.

Brainstealer Dragon

Flying
At the beginning of your end step, exile the top card of each opponent's library. You may play those cards for as long as they remain exiled. If you cast a spell this way, you may spend mana as though it were mana of any color to cast it.
Whenever a nonland permanent an opponent owns enters the battlefield under your control, they lose life equal to its mana value.

Infernal Grasp

Destroy target creature. You lose 2 life.

Nashi, Moon Sage's Scion

Ninjutsu {3}{B} ({3}{B}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.)
Whenever Nashi, Moon Sage's Scion deals combat damage to a player, exile the top card of each player's library. Until end of turn, you may play one of those cards. If you cast a spell this way, pay life equal to its mana value rather than paying its mana cost.

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.

Nirkana Revenant

Whenever you tap a Swamp for mana, add an additional {B}.
{B}: Nirkana Revenant gets +1/+1 until end of turn.

Braids, Arisen Nightmare

At the beginning of your end step, you may sacrifice an artifact, creature, enchantment, land, or planeswalker. If you do, each opponent may sacrifice a permanent that shares a card type with it. For each opponent who doesn't, that player loses 2 life and you draw a card.

Burnished Hart

{3}, Sacrifice Burnished Hart: Search your library for up to two basic land cards, put them onto the battlefield tapped, then shuffle.

Fellwar Stone

{T}: Add one mana of any color that a land an opponent controls could produce.

Blade of Selves

Equipped creature has myriad. (Whenever it attacks, for each opponent other than defending player, you may create a token copy that's tapped and attacking that player or a planeswalker they control. Exile the tokens at end of combat.)
Equip {4}

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.

Conjurer's Closet

At the beginning of your end step, you may exile target creature you control, then return that card to the battlefield under your control.

Night's Whisper

Demonic Tutor

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

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.