Urborg, Tomb of Yawgmoth

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

Paragon of Open Graves

Other black creatures you control get +1/+1.
{2}{B}, {T}: Another target black creature you control gains deathtouch until end of turn. (Any amount of damage it deals to a creature is enough to destroy it.)

Glen Elendra Liege

Flying
Other blue creatures you control get +1/+1.
Other black creatures you control get +1/+1.

Marauding Blight-Priest

Whenever you gain life, each opponent loses 1 life.

Prince of Thralls

Whenever a permanent an opponent controls is put into a graveyard, put that card onto the battlefield under your control unless that opponent pays 3 life.

Orcus, Prince of Undeath

Flying, trample
When Orcus enters, choose one —
• Each other creature gets -X/-X until end of turn. You lose X life.
• Return up to X target creature cards with total mana value X or less from your graveyard to the battlefield. They gain haste until end of turn.

Vito, Thorn of the Dusk Rose

Whenever you gain life, target opponent loses that much life.
{3}{B}{B}: Creatures you control gain lifelink until end of turn.

Callidus Assassin

Flash
Polymorphine — You may have this creature enter tapped as a copy of any creature on the battlefield, except it has "When this creature enters, destroy up to one other target creature with the same name as this creature."

Exotic Orchard

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

Sol Ring

Shipwreck Marsh

This land enters tapped unless you control two or more other lands.
{T}: Add {U} or {B}.

Glass of the Guildpact

Multicolored creatures you control get +1/+1.

Dragonlord Silumgar

Flying, deathtouch
When Dragonlord Silumgar enters, gain control of target creature or planeswalker for as long as you control Dragonlord Silumgar.

Jet Medallion

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

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.

Blood Crypt

({T}: Add {B} or {R}.)
As this land enters, you may pay 2 life. If you don't, it enters tapped.

Starscape Cleric

Offspring {2}{B} (You may pay an additional {2}{B} as you cast this spell. If you do, when this creature enters, create a 1/1 token copy of it.)
Flying
This creature can't block.
Whenever you gain life, each opponent loses 1 life.

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.

Bad Moon

Mahadi, Emporium Master

At the beginning of your end step, create a Treasure token for each creature that died this turn. (It's an artifact with "{T}, Sacrifice this token: Add one mana of any color.")

Talisman of Dominance

{T}: Add {C}.
{T}: Add {U} or {B}. This artifact deals 1 damage to you.

Heraldic Banner

As this artifact enters, choose a color.
Creatures you control of the chosen color get +1/+0.
{T}: Add one mana of the chosen color.

Rakdos Signet

Gloomlake Verge

{T}: Add {U}.
{T}: Add {B}. Activate only if you control an Island or a Swamp.

Swamp

Blazemire Verge

{T}: Add {B}.
{T}: Add {R}. Activate only if you control a Swamp or a Mountain.

Defiler of Souls

Flying
At the beginning of each player's upkeep, that player sacrifices a monocolored creature of their choice.

Nazar, the Velvet Fang

Menace (This creature can't be blocked except by two or more creatures.)
Whenever you gain life, put a feeding counter on Nazar.
Whenever Nazar attacks, you may remove three feeding counters from it. If you do, you draw three cards and you lose 3 life.

Master of Cruelties

First strike, deathtouch
This creature can only attack alone.
Whenever this creature attacks a player and isn't blocked, that player's life total becomes 1. This creature assigns no combat damage this combat.

Starlit Soothsayer

Flying
At the beginning of your end step, if you gained or lost life this turn, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)

Sulfurous Springs

{T}: Add {C}.
{T}: Add {B} or {R}. This land deals 1 damage to you.

Caged Sun

As this artifact 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.

Hostage Taker

When this creature enters, exile another target creature or artifact until this creature leaves the battlefield. You may cast that card for as long as it remains exiled, and mana of any type can be spent to cast that spell.

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.

Corrosive Mentor

Black creatures you control have wither. (They deal damage to creatures in the form of -1/-1 counters.)

Scent of Nightshade

Reveal any number of black cards in your hand. Target creature gets -X/-X until end of turn, where X is the number of cards revealed this way.

Xander's Lounge

({T}: Add {U}, {B}, or {R}.)
This land enters tapped.
Cycling {3} ({3}, Discard this card: Draw a card.)

Shadowmage Infiltrator

Fear (This creature can't be blocked except by artifact creatures and/or black creatures.)
Whenever this creature deals combat damage to a player, you may draw a card.

Vial Smasher the Fierce

Whenever you cast your first spell each turn, choose an opponent at random. Vial Smasher deals damage equal to that spell's mana value to that player or a planeswalker that player controls.
Partner (You can have two commanders if both have partner.)

Mishra, Claimed by Gix

Whenever you attack, each opponent loses X life and you gain X life, where X is the number of attacking creatures. If Mishra, Claimed by Gix and a creature named Phyrexian Dragon Engine are attacking, and you both own and control them, exile them, then meld them into Mishra, Lost to Phyrexia. It enters tapped and attacking.

Sol'kanar the Swamp King

Swampwalk (This creature can't be blocked as long as defending player controls a Swamp.)
Whenever a player casts a black spell, you gain 1 life.

Gollum, Obsessed Stalker

Skulk (This creature can't be blocked by creatures with greater power.)
At the beginning of your end step, each opponent dealt combat damage this game by a creature named Gollum, Obsessed Stalker loses life equal to the amount of life you gained this turn.

Ertai Resurrected

Flash
When Ertai Resurrected enters, choose up to one —
• Counter target spell, activated ability, or triggered ability. Its controller draws a card.
• Destroy another target creature or planeswalker. Its controller draws a card.

Rooftop Bypass

Whenever one or more nontoken creatures you control deal combat damage to a player, create a 1/1 black Assassin creature token with menace. (It can't be blocked except by two or more creatures.)

Obsidian Obelisk

This artifact enters tapped.
{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to cast a multicolored spell.

Soot Imp

Flying
Whenever a player casts a nonblack spell, that player loses 1 life.

Underground River

{T}: Add {C}.
{T}: Add {U} or {B}. This land deals 1 damage to you.

Haunted Ridge

This land enters tapped unless you control two or more other lands.
{T}: Add {B} or {R}.

Talisman of Indulgence

{T}: Add {C}.
{T}: Add {B} or {R}. This artifact deals 1 damage to you.

Chaos Defiler

Trample
Battle Cannon — When this creature enters or dies, for each opponent, choose a nonland permanent that player controls. Destroy one of them chosen at random.

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}.

Countersquall

Counter target noncreature spell. Its controller loses 2 life.

Fellwar Stone

Too Greedily, Too Deep

Put target creature card from a graveyard onto the battlefield under your control. That creature deals damage equal to its power to each other creature.

Path of Ancestry

This land enters tapped.
{T}: Add one mana of any color in your commander's color identity. When that mana is spent to cast a creature spell that shares a creature type with your commander, scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Dimir Signet

Witch of the Moors

Deathtouch
At the beginning of your end step, if you gained life this turn, each opponent sacrifices a creature of their choice and you return up to one target creature card from your graveyard to your hand.

Watery Grave

({T}: Add {U} or {B}.)
As this land enters, you may pay 2 life. If you don't, it enters tapped.

The Lord of Pain

Menace
Your opponents can't gain life.
Whenever a player casts their first spell each turn, choose another target player. The Lord of Pain deals damage equal to that spell's mana value to the chosen player.

Halo Forager

Flying
When this creature enters, you may pay {X}. When you do, you may cast target instant or sorcery card with mana value X from a graveyard without paying its mana cost. If that spell would be put into a graveyard, exile it instead.

Toxrill, the Corrosive

At the beginning of each end step, put a slime counter on each creature you don't control.
Creatures you don't control get -1/-1 for each slime counter on them.
Whenever a creature you don't control with a slime counter on it dies, create a 1/1 black Slug creature token.
{U}{B}, Sacrifice a Slug: Draw a card.

Morphic Pool

This land enters tapped unless you have two or more opponents.
{T}: Add {U} or {B}.

Crowd of Cinders

Fear (This creature can't be blocked except by artifact creatures and/or black creatures.)
Crowd of Cinders's power and toughness are each equal to the number of black permanents 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.

Mountain

Siphon Insight

Look at the top two cards of target opponent's library. Exile one of them face down and put the other on the bottom of that library. You may play the exiled card for as long as it remains exiled, and you may spend mana as though it were mana of any color to cast that spell.
Flashback {1}{U}{B}

Expedition Map

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

Crumbling Necropolis

This land enters tapped.
{T}: Add {U}, {B}, or {R}.

Memory Plunder

You may cast target instant or sorcery card from an opponent's graveyard without paying its mana cost.

Arcane Signet

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

Basim Ibn Ishaq

Whenever you cast a historic spell, draw a card. Basim Ibn Ishaq can't be blocked this turn. This ability triggers only once each turn. (Artifacts, legendaries, and Sagas are historic.)
Whenever Basim Ibn Ishaq deals combat damage to a player, put a +1/+1 counter on it.

Bojuka Bog

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

Grixis Grimblade

As long as you control another multicolored permanent, this creature gets +1/+1 and has deathtouch. (Any amount of damage it deals to a creature is enough to destroy that creature.)

Urza's Filter

Multicolored spells cost {2} less to cast.

Reiver Demon

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

Cruel Ultimatum

Target opponent sacrifices a creature of their choice, discards three cards, then loses 5 life. You return a creature card from your graveyard to your hand, draw three cards, then gain 5 life.

Luxury Suite

This land enters tapped unless you have two or more opponents.
{T}: Add {B} or {R}.

Command Tower

Ashenmoor Liege

Other black creatures you control get +1/+1.
Other red creatures you control get +1/+1.
Whenever this creature becomes the target of a spell or ability an opponent controls, that player loses 4 life.

Kaervek the Merciless

Whenever an opponent casts a spell, Kaervek deals damage equal to that spell's mana value to any target.

Island

Mayhem Devil

Whenever a player sacrifices a permanent, this creature deals 1 damage to any target.

Baleful Strix

Flying, deathtouch
When this creature enters, draw a card.

Relic of Sauron

{T}: Add two mana in any combination of {U}, {B}, and/or {R}.
{3}, {T}: Draw two cards, then discard a card.