Ob Nixilis, the Adversary

Casualty X. The copy isn't legendary and has starting loyalty X. (As you cast this spell, you may sacrifice a creature with power X. When you do, copy this spell. The copy becomes a token.)
+1: Each opponent loses 2 life unless they discard a card. If you control a Demon or Devil, you gain 2 life.
−2: Create a 1/1 red Devil creature token with "When this token dies, it deals 1 damage to any target."
−7: Target player draws seven cards and loses 7 life.

Chaos Warp

The owner of target permanent shuffles it into their library, then reveals the top card of their library. If it's a permanent card, they put it onto the battlefield.

Canoptek Scarab Swarm

Flying
Feeder Mandibles — When this creature enters, exile target player's graveyard. For each artifact or land card exiled this way, create a 1/1 colorless Insect artifact creature token with flying.

Mind Stone

{T}: Add {C}.
{1}, {T}, Sacrifice this artifact: Draw a card.

Shattered Yard

At the beginning of your end step, this Room deals 1 damage to each opponent.
(You may cast either half. That door unlocks on the battlefield. As a sorcery, you may pay the mana cost of a locked door to unlock it.)

Glassworks

When you unlock this door, this Room deals 4 damage to target creature an opponent controls.
(You may cast either half. That door unlocks on the battlefield. As a sorcery, you may pay the mana cost of a locked door to unlock it.)

Glassworks // Shattered Yard

Chandra's Incinerator

This spell costs {X} less to cast, where X is the total amount of noncombat damage dealt to your opponents this turn.
Trample
Whenever a source you control deals noncombat damage to an opponent, this creature deals that much damage to target creature or planeswalker that player controls.

Loyal Subordinate

Menace (This creature can't be blocked except by two or more creatures.)
Lieutenant — At the beginning of combat on your turn, if you control your commander, each opponent loses 3 life.

Sanctum of Stone Fangs

At the beginning of your first main phase, each opponent loses X life and you gain X life, where X is the number of Shrines you control.

Ribbons

Aftermath (Cast this spell only from your graveyard. Then exile it.)
Each opponent loses X life.

Cut // Ribbons

Rakdos Signet

Exsanguinate

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

Commander's Sphere

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

Cryptborn Horror

Trample
This creature enters with X +1/+1 counters on it, where X is the total life lost by your opponents this turn.

Dire Fleet Ravager

Menace, deathtouch
When this creature enters, each player loses a third of their life, rounded up.

Aurora of Emrakul

Flying, deathtouch
Whenever this creature attacks, each opponent loses 3 life.

Cryptolith Fragment

This artifact enters tapped.
{T}: Add one mana of any color. Each player loses 1 life.
At the beginning of your upkeep, if each player has 10 or less life, transform this artifact.

Cryptolith Fragment // Aurora of Emrakul

Lobber Crew

Defender
{T}: This creature deals 1 damage to each opponent.
Whenever you cast a multicolored spell, untap this creature.

Starscream, Seeker Leader

Living metal (During your turn, this Vehicle is also a creature.)
Flying, menace, haste
Whenever Starscream deals combat damage to a player, if there is no monarch, that player becomes the monarch.
Whenever you become the monarch, convert Starscream.

Starscream, Power Hungry

More Than Meets the Eye {2}{B} (You may cast this card converted for {2}{B}.)
Flying
Whenever you draw a card, if you're the monarch, target opponent loses 2 life.
Whenever one or more creatures deal combat damage to you, convert Starscream.

Starscream, Power Hungry // Starscream, Seeker Leader

Exotic Orchard

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

Demonic Tutor

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

Mountain

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.

Valakut Stoneforge

Valakut Awakening

Put any number of cards from your hand on the bottom of your library, then draw that many cards plus one.

Valakut Awakening // Valakut Stoneforge

Plague Spitter

At the beginning of your upkeep, this creature deals 1 damage to each creature and each player.
When this creature dies, it deals 1 damage to each creature and each player.

Smoldering Marsh

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

Urborg, Tomb of Yawgmoth

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

Shadowblood Ridge

Florian, Voldaren Scion

First strike
At the beginning of each of your postcombat main phases, look at the top X cards of your library, where X is the total amount of life your opponents lost this turn. Exile one of those cards and put the rest on the bottom of your library in a random order. You may play the exiled card this turn.

Swamp

Arcane Signet

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

Graven Cairns

{T}: Add {C}.
{B/R}, {T}: Add {B}{B}, {B}{R}, or {R}{R}.

Tainted Peak

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

Jeska's Will

Choose one. If you control a commander as you cast this spell, you may choose both instead.
• Add {R} for each card in target opponent's hand.
• Exile the top three cards of your library. You may play them this turn.

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.

Cabal Coffers

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

Talisman of Indulgence

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

Bojuka Bog

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

Rolling Earthquake

Rolling Earthquake deals X damage to each creature without horsemanship and each player.

Blood Tithe

Each opponent loses 3 life. You gain life equal to the life lost this way.

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.)

Leechridden Swamp

({T}: Add {B}.)
This land enters tapped.
{B}, {T}: Each opponent loses 1 life. Activate only if you control two or more black permanents.

Foreboding Ruins

As this land enters, you may reveal a Swamp or Mountain card from your hand. If you don't, this land enters tapped.
{T}: Add {B} or {R}.

Sol Ring

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.

Sanguine Syphoner

Whenever this creature attacks, each opponent loses 1 life and you gain 1 life.

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.

Fabled Passage

{T}, Sacrifice this land: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle. Then if you control four or more lands, untap that land.

Giggling Skitterspike

Indestructible
Whenever this creature attacks, blocks, or becomes the target of a spell, it deals damage equal to its power to each opponent.
{5}: Monstrosity 5. (If this creature isn't monstrous, put five +1/+1 counters on it and it becomes monstrous.)

Archfiend of Despair

Flying
Your opponents can't gain life.
At the beginning of each end step, each opponent loses life equal to the life that player lost this turn. (Damage causes loss of life.)

Flame Rift

Flame Rift deals 4 damage to each player.

Blasphemous Act

This spell costs {1} less to cast for each creature on the battlefield.
Blasphemous Act deals 13 damage to each creature.

Descent into Avernus

At the beginning of your upkeep, put two descent counters on this enchantment. Then each player creates X Treasure tokens and this enchantment deals X damage to each player, where X is the number of descent counters on this enchantment.

Fear of Burning Alive

When this creature enters, it deals 4 damage to each opponent.
Delirium — Whenever a source you control deals noncombat damage to an opponent, if there are four or more card types among cards in your graveyard, this creature deals that amount of damage to target creature that player controls.

Sulfurous Springs

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

Gnoll War Band

This spell costs {1} less to cast for each opponent who was dealt damage this turn.
Menace
Myriad (Whenever this creature 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.)

Temporal Extortion

When you cast this spell, any player may pay half their life, rounded up. If a player does, counter Temporal Extortion.
Take an extra turn after this one.

Light Up the Stage

Spectacle {R} (You may cast this spell for its spectacle cost rather than its mana cost if an opponent lost life this turn.)
Exile the top two cards of your library. Until the end of your next turn, you may play those cards.

Fellwar Stone

Temple of Malice

This land enters tapped.
When this land enters, scry 1. (Look at the top card of your library. You may put that card on the bottom.)
{T}: Add {B} or {R}.

Rakdos Charm

Choose one —
• Exile target player's graveyard.
• Destroy target artifact.
• Each creature deals 1 damage to its controller.

Cursed Mirror

{T}: Add {R}.
As this artifact enters, you may have it become a copy of any creature on the battlefield until end of turn, except it has haste.

Sinister Monolith

At the beginning of combat on your turn, each opponent loses 1 life and you gain 1 life.
{T}, Pay 2 life, Sacrifice this artifact: Draw two cards. Activate only as a sorcery.

Subversion

At the beginning of your upkeep, each opponent loses 1 life. You gain life equal to the life lost this way.

Court of Ire

When this enchantment enters, you become the monarch.
At the beginning of your upkeep, this enchantment deals 2 damage to any target. If you're the monarch, it deals 7 damage instead.

Creeping Bloodsucker

At the beginning of your upkeep, this creature deals 1 damage to each opponent. You gain life equal to the damage dealt this way.

Slagstorm

Choose one —
• Slagstorm deals 3 damage to each creature.
• Slagstorm deals 3 damage to each player.

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.)

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.)

Blood for the Blood God!

This spell costs {1} less to cast for each creature that died this turn.
Discard your hand, then draw eight cards. Blood for the Blood God! deals 8 damage to each opponent. Exile Blood for the Blood God!

Spawn of Mayhem

Spectacle {1}{B}{B} (You may cast this spell for its spectacle cost rather than its mana cost if an opponent lost life this turn.)
Flying, trample
At the beginning of your upkeep, this creature deals 1 damage to each player. Then if you have 10 or less life, put a +1/+1 counter on this creature.

Night Market Lookout

Whenever this creature becomes tapped, each opponent loses 1 life and you gain 1 life.

Drossclaw

Living weapon (When this Equipment enters, create a 0/0 black Phyrexian Germ creature token, then attach this to it.)
Equipped creature gets +1/+1.
Whenever equipped creature attacks, each opponent loses 1 life.
Equip {2}

Mount Doom

{T}, Pay 1 life: Add {B} or {R}.
{1}{B}{R}, {T}: Mount Doom deals 1 damage to each opponent.
{5}{B}{R}, {T}, Sacrifice Mount Doom and a legendary artifact: Choose up to two creatures, then destroy the rest. Activate only as a sorcery.

Chandra's Spitfire

Flying
Whenever an opponent is dealt noncombat damage, this creature gets +3/+0 until end of turn.

Mardu Shadowspear

Whenever this creature attacks, each opponent loses 1 life.
Dash {1}{B} (You may cast this spell for its dash cost. If you do, it gains haste, and it's returned from the battlefield to its owner's hand at the beginning of the next end step.)

Command Tower

Court of Ambition

When this enchantment enters, you become the monarch.
At the beginning of your upkeep, each opponent loses 3 life unless they discard a card. If you're the monarch, instead each opponent loses 6 life unless they discard two cards.

Blood Tribute

Kicker—Tap an untapped Vampire you control. (You may tap a Vampire you control in addition to any other costs as you cast this spell.)
Target opponent loses half their life, rounded up. If this spell was kicked, you gain life equal to the life lost this way.

Syphon Soul

Syphon Soul deals 2 damage to each other player. You gain life equal to the damage dealt this way.

Stormfist Crusader

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

Dragonskull Summit

This land enters tapped unless you control a Swamp or a Mountain.
{T}: Add {B} or {R}.

Sanctum Seeker

Whenever a Vampire you control attacks, each opponent loses 1 life and you gain 1 life.

Firebrand Archer

Whenever you cast a noncreature spell, this creature deals 1 damage to each opponent.

Haunted Ridge

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

Nettle Drone

Devoid (This card has no color.)
{T}: This creature deals 1 damage to each opponent.
Whenever you cast a colorless spell, untap this creature.

Theater of Horrors

At the beginning of your upkeep, exile the top card of your library.
During your turn, if an opponent lost life this turn, you may play lands and cast spells from among cards exiled with this enchantment.
{3}{R}: This enchantment deals 1 damage to target opponent or planeswalker.

Vicious Conquistador

Whenever this creature attacks, each opponent loses 1 life.

Ill-Gotten Inheritance

At the beginning of your upkeep, this enchantment deals 1 damage to each opponent and you gain 1 life.
{5}{B}, Sacrifice this enchantment: It deals 4 damage to target opponent and you gain 4 life.

Warlock Class

(Gain the next level as a sorcery to add its ability.)
At the beginning of your end step, if a creature died this turn, each opponent loses 1 life.
{1}{B}: Level 2
When this Class becomes level 2, look at the top three cards of your library. Put one of them into your hand and the rest into your graveyard.
{6}{B}: Level 3
At the beginning of your end step, each opponent loses life equal to the life they lost this turn. (Damage causes loss of life.)

Sign in Blood

Target player draws two cards and loses 2 life.

Shivan Gorge

{T}: Add {C}.
{2}{R}, {T}: Shivan Gorge deals 1 damage to each opponent.

Mana Geyser

Add {R} for each tapped land your opponents control.

General Kreat, the Boltbringer

Whenever one or more Goblins you control attack, create a 1/1 red Goblin creature token that's tapped and attacking.
Whenever another creature you control enters, General Kreat deals 1 damage to each opponent.

Night's Whisper

Blood Crypt

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

Thermo-Alchemist

Defender
{T}: This creature deals 1 damage to each opponent.
Whenever you cast an instant or sorcery spell, untap this creature.