Consider

Semblance Anvil

Imprint — When this artifact enters, you may exile a nonland card from your hand.
Spells you cast that share a card type with the exiled card cost {2} less to cast.

Have

Dread Presence

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

Sheoldred, the Apocalypse

Deathtouch
Whenever you draw a card, you gain 2 life.
Whenever an opponent draws a card, they lose 2 life.

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.

Terrain Generator

{T}: Add {C}.
{2}, {T}: You may put a basic land card from your hand onto the battlefield tapped.

The True Scriptures

(As this Saga enters and after your draw step, add a lore counter.)
I — For each opponent, destroy up to one target creature or planeswalker that player controls.
II — Each opponent discards three cards, then mills three cards.
III — Put all creature cards from all graveyards onto the battlefield under your control. Exile this Saga, then return it to the battlefield (front face up).

Sheoldred

Menace
When Sheoldred enters, each opponent sacrifices a nontoken creature or planeswalker of their choice.
{4}{B}: Exile Sheoldred, then return it to the battlefield transformed under its owner's control. Activate only as a sorcery and only if an opponent has eight or more cards in their graveyard.

Sheoldred // The True Scriptures

Deserted Temple

{T}: Add {C}.
{1}, {T}: Untap target land.

Oubliette

When this enchantment enters, target creature phases out until this enchantment leaves the battlefield. Tap that creature as it phases in this way. (Auras and Equipment phase out with it. While permanents are phased out, they're treated as though they don't exist.)

Myriad Landscape

This land enters tapped.
{T}: Add {C}.
{2}, {T}, Sacrifice this land: Search your library for up to two basic land cards that share a land type, put them onto the battlefield tapped, then shuffle.

Urborg, Tomb of Yawgmoth

Each land is a Swamp in addition to its other land types.

Kozilek, the Great Distortion

When you cast this spell, if you have fewer than seven cards in hand, draw cards equal to the difference.
Menace
Discard a card with mana value X: Counter target spell with mana value X.

Bojuka Bog

This land enters tapped.
When this land enters, exile target player's graveyard.
{T}: Add {B}.

Strip Mine

{T}: Add {C}.
{T}, Sacrifice this land: Destroy target land.

Urza's Incubator

As this artifact enters, choose a creature type.
Creature spells of the chosen type cost {2} less to cast.

Orc Sureshot

Whenever another creature you control enters, target creature an opponent controls gets -1/-1 until end of turn.

Breach the Multiverse

Each player mills ten cards. For each player, choose a creature or planeswalker card in that player's graveyard. Put those cards onto the battlefield under your control. Then each creature you control becomes a Phyrexian in addition to its other types.

Vanquisher's Banner

As this artifact enters, choose a creature type.
Creatures you control of the chosen type get +1/+1.
Whenever you cast a creature spell of the chosen type, draw a card.

The Fire Nation Drill

Trample
When The Fire Nation Drill enters, you may tap it. When you do, destroy target creature with power 4 or less.
{1}: Permanents your opponents control lose hexproof and indestructible until end of turn.
Crew 2

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.

Emrakul, the World Anew

When you cast this spell, gain control of all creatures target player controls.
Flying, protection from spells and from permanents that were cast this turn
When Emrakul leaves the battlefield, sacrifice all creatures you control.
Madness—Pay six {C}.

Thought Vessel

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

The Darkness Crystal

Black spells you cast cost {1} less to cast.
If a nontoken creature an opponent controls would die, instead exile it and you gain 2 life.
{4}{B}{B}, {T}: Put target creature card exiled with The Darkness Crystal onto the battlefield tapped under your control with two additional +1/+1 counters on it.

Cabal Stronghold

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

Cabal Coffers

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

Aetherflux Reservoir

Whenever you cast a spell, you gain 1 life for each spell you've cast this turn.
Pay 50 life: This artifact deals 50 damage to any target.

Feed the Swarm

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

Decree of Pain

Destroy all creatures. They can't be regenerated. Draw a card for each creature destroyed this way.
Cycling {3}{B}{B} ({3}{B}{B}, Discard this card: Draw a card.)
When you cycle this card, all creatures get -2/-2 until end of turn.

Flare of Malice

You may sacrifice a nontoken black creature rather than pay this spell's mana cost.
Each opponent sacrifices a creature or planeswalker with the greatest mana value among creatures and planeswalkers they control.

Relic of Legends

{T}: Add one mana of any color.
Tap an untapped legendary creature you control: Add one mana of any color.

Hagra Broodpit

Hagra Mauling

This spell costs {1} less to cast if an opponent controls no basic lands.
Destroy target creature.

Hagra Mauling // Hagra Broodpit

The Immortal Sun

Players can't activate planeswalkers' loyalty abilities.
At the beginning of your draw step, draw an additional card.
Spells you cast cost {1} less to cast.
Creatures you control get +1/+1.

Navigation Orb

{2}, {T}, Sacrifice this artifact: Search your library for up to two basic land cards and/or Gate cards, reveal those cards, put one onto the battlefield tapped and the other into your hand, then shuffle.

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.

Blood Money

Destroy all creatures. For each nontoken creature destroyed this way, you create a tapped Treasure token.

Blasphemous Edict

You may pay {B} rather than pay this spell's mana cost if there are thirteen or more creatures on the battlefield.
Each player sacrifices thirteen creatures of their choice.

Sol Ring

Ulamog, the Ceaseless Hunger

When you cast this spell, exile two target permanents.
Indestructible
Whenever Ulamog attacks, defending player exiles the top twenty cards of their library.

Cabal Paladin

Whenever you cast a historic spell, this creature deals 2 damage to each opponent. (Artifacts, legendaries, and Sagas are historic.)

Jet Medallion

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

Vedalken Orrery

You may cast spells as though they had flash.

Fell Mire

As this land enters, you may pay 3 life. If you don't, it enters tapped.
{T}: Add {B}.

Fell the Profane

Fell the Profane // Fell Mire

Kozilek, Butcher of Truth

When you cast this spell, draw four cards.
Annihilator 4 (Whenever this creature attacks, defending player sacrifices four permanents of their choice.)
When Kozilek is put into a graveyard from anywhere, its owner shuffles their graveyard into their library.

Oketra's Monument

White creature spells you cast cost {1} less to cast.
Whenever you cast a creature spell, create a 1/1 white Warrior creature token with vigilance.

Alhammarret's Archive

If you would gain life, you gain twice that much life instead.
If you would draw a card except the first one you draw in each of your draw steps, draw two cards instead.

Diregraf Colossus

This creature enters with a +1/+1 counter on it for each Zombie card in your graveyard.
Whenever you cast a Zombie spell, create a tapped 2/2 black Zombie creature token.

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.)

Solemn Simulacrum

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

Withering Torment

Destroy target creature or enchantment. You lose 2 life.

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.

Infernal Grasp

Destroy target creature. You lose 2 life.

Prism Ring

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

The Soul Stone

Indestructible
{T}: Add {B}.
{6}{B}, {T}, Exile a creature you control: Harness The Soul Stone. (Once harnessed, its ∞ ability is active.)
∞ — At the beginning of your upkeep, return target creature card from your graveyard to the battlefield.

Thespian's Stage

{T}: Add {C}.
{2}, {T}: This land becomes a copy of target land, except it has this ability.

Archenemy's Charm

Choose one —
• Exile target creature or planeswalker.
• Return one or two target creature and/or planeswalker cards from your graveyard to your hand.
• Put two +1/+1 counters on target creature you control. It gains lifelink until end of turn.

Introduction to Annihilation

Exile target nonland permanent. Its controller draws a card.

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.

Heartless Conscription

Exile all creatures. For each card exiled this way, you may play that card for as long as it remains exiled, and mana of any type can be spent to cast that spell. Exile Heartless Conscription.

Greed

Noxious Ghoul

Whenever this creature or another Zombie enters, all non-Zombie creatures get -1/-1 until end of turn.

Ayara, First of Locthwain

Whenever Ayara or another black creature you control enters, each opponent loses 1 life and you gain 1 life.
{T}, Sacrifice another black creature: Draw a card.

Agadeem, the Undercrypt

Agadeem's Awakening

Return from your graveyard to the battlefield any number of target creature cards that each have a different mana value X or less.

Agadeem's Awakening // Agadeem, the Undercrypt

Wasteland

{T}: Add {C}.
{T}, Sacrifice this land: Destroy target nonbasic land.

Zenith Chronicler

Whenever a player casts their first multicolored spell each turn, each other player draws a card.

Ancient Cellarspawn

Each spell you cast that's a Demon, Horror, or Nightmare costs {1} less to cast.
Whenever you cast a spell, if the amount of mana spent to cast it was less than its mana value, target opponent loses life equal to the difference.

Arcane Signet

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

Burnished Hart

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

Hithlain Rope

This artifact can't be sacrificed.
{1}, {T}: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle. The player to your right gains control of this artifact.
{2}, {T}: Draw a card. The player to your right gains control of this artifact.

Planar Gate

Creature spells you cast cost {2} less to cast.

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.)

Meathook Massacre II

When Meathook Massacre II enters, each player sacrifices X creatures of their choice.
Whenever a creature you control dies, you may pay 3 life. If you do, return that card under your control with a finality counter on it.
Whenever a creature an opponent controls dies, they may pay 3 life. If they don't, return that card under your control with a finality counter on it.

Tinybones Joins Up

When Tinybones Joins Up enters, any number of target players each discard a card.
Whenever a legendary creature you control enters, any number of target players each mill a card and lose 1 life.

V.A.T.S.

Split second (As long as this spell is on the stack, players can't cast spells or activate abilities that aren't mana abilities.)
Choose any number of target creatures with equal toughness. Destroy the chosen creatures.

Syphon Mind

Each other player discards a card. You draw a card for each card discarded this way.

The Sibsig Ceremony

Creature spells you cast cost {2} less to cast.
Whenever a creature you control enters, if you cast it, destroy that creature, then create a 2/2 black Zombie Druid creature token.

Honor-Worn Shaku

{T}: Add {C}.
Tap an untapped legendary permanent you control: Untap this artifact.

World Map

{1}, {T}, Sacrifice this artifact: Search your library for a basic land card, reveal it, put it into your hand, then shuffle.
{3}, {T}, Sacrifice this artifact: Search your library for a land card, reveal it, put it into your hand, then shuffle.

Damnation

Destroy all creatures. They can't be regenerated.

Jhoira's Familiar

Flying
Historic spells you cast cost {1} less to cast. (Artifacts, legendaries, and Sagas are historic.)

Snow-Covered Swamp

Manascape Refractor

This artifact enters tapped.
This artifact has all activated abilities of all lands on the battlefield.
You may spend mana as though it were mana of any color to pay the activation costs of this artifact's abilities.

Emrakul, the Promised End

This spell costs {1} less to cast for each card type among cards in your graveyard.
When you cast this spell, you gain control of target opponent during that player's next turn. After that turn, that player takes an extra turn.
Flying, trample, protection from instants

Stone Calendar

Heartless Summoning

Creature spells you cast cost {2} less to cast.
Creatures you control get -1/-1.

Toxic Deluge

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

Acererak the Archlich

When Acererak enters, if you haven't completed Tomb of Annihilation, return Acererak to its owner's hand and venture into the dungeon.
Whenever Acererak attacks, for each opponent, you create a 2/2 black Zombie creature token unless that player sacrifices a creature of their choice.

Portal to Phyrexia

When this artifact enters, each opponent sacrifices three creatures of their choice.
At the beginning of your upkeep, put target creature card from a graveyard onto the battlefield under your control. It's a Phyrexian in addition to its other types.

Demon's Horn

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

Zodiark, Umbral God

Indestructible
When Zodiark enters, each player sacrifices half the non-God creatures they control of their choice, rounded down.
Whenever a player sacrifices another creature, put a +1/+1 counter on Zodiark.

Charcoal Diamond

This artifact enters tapped.
{T}: Add {B}.

Erebos, God of the Dead

Indestructible
As long as your devotion to black is less than five, Erebos isn't a creature. (Each {B} in the mana costs of permanents you control counts toward your devotion to black.)
Your opponents can't gain life.
{1}{B}, Pay 2 life: Draw a card.

Expedition Map

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

Soul Shatter

Each opponent sacrifices a creature or planeswalker with the greatest mana value among creatures and planeswalkers they control.

Valgavoth, Terror Eater

Flying, lifelink
Ward—Sacrifice three nonland permanents.
If a card you didn't control would be put into an opponent's graveyard from anywhere, exile it instead.
During your turn, you may play cards exiled with Valgavoth. If you cast a spell this way, pay life equal to its mana value rather than pay its mana cost.

Wayfarer's Bauble

{2}, {T}, Sacrifice this artifact: Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Cloud Key

As this artifact enters, choose artifact, creature, enchantment, instant, or sorcery.
Spells you cast of the chosen type cost {1} less to cast.

Diresight

Surveil 2, then draw two cards. You lose 2 life. (To 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.)

Throne of Eldraine

As Throne of Eldraine enters, choose a color.
{T}: Add four mana of the chosen color. Spend this mana only to cast monocolored spells of that color.
{3}, {T}: Draw two cards. Spend only mana of the chosen color to activate this ability.