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.)

Aetherflux Reservoir

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

Reanimate

Put target creature card from a graveyard onto the battlefield under your control. You lose life equal to its mana value.

Sulfurous Springs

{T}: Add {C}.
{T}: Add {B} or {R}. Sulfurous Springs deals 1 damage to you.

Demonlord Belzenlok

Flying, trample
When Demonlord Belzenlok enters, exile cards from the top of your library until you exile a nonland card, then put that card into your hand. If the card's mana value is 4 or greater, repeat this process. Demonlord Belzenlok deals 1 damage to you for each card put into your hand this way.

Swiftfoot Boots

Equipped creature has hexproof and haste. (It can't be the target of spells or abilities your opponents control. It can attack and {T} no matter when it came under your control.)
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Counterspell

Grievous Wound

Enchant player
Enchanted player can't gain life.
Whenever enchanted player is dealt damage, they lose half their life, rounded up.

Entomb

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

Living Death

Each player exiles all creature cards from their graveyard, then sacrifices all creatures they control, then puts all cards they exiled this way onto the battlefield.

Bloodthirsty Conqueror

Flying, deathtouch
Whenever an opponent loses life, you gain that much life. (Damage causes loss of life.)

Valgavoth, Harrower of Souls

Flying
Ward—Pay 2 life.
Whenever an opponent loses life for the first time during each of their turns, put a +1/+1 counter on Valgavoth, Harrower of Souls and draw a card.

Bojuka Bog

Bojuka Bog enters tapped.
When Bojuka Bog enters, exile target player's graveyard.
{T}: Add {B}.

Spiteful Banditry

When Spiteful Banditry enters, it deals X damage to each creature.
Whenever one or more creatures your opponents control die, you create a Treasure token. This ability triggers only once each turn.

Secluded Courtyard

As this land enters, choose a creature type.
{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to cast a creature spell of the chosen type or activate an ability of a creature source of the chosen type.

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.)

Liliana's Contract

When Liliana's Contract enters, you draw four cards and you lose 4 life.
At the beginning of your upkeep, if you control four or more Demons with different names, you win the game.

Deflecting Swat

If you control a commander, you may cast this spell without paying its mana cost.
You may choose new targets for target spell or ability.

Gilded Lotus

Island

Vilis, Broker of Blood

Flying
{B}, Pay 2 life: Target creature gets -1/-1 until end of turn.
Whenever you lose life, draw that many cards. (Damage causes loss of life.)

Chromatic Lantern

Lands you control have "{T}: Add one mana of any color."
{T}: Add one mana of any color.

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.

Burnished Hart

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

Bloodletter of Aclazotz

Flying
If an opponent would lose life during your turn, they lose twice that much life instead. (Damage causes loss of life.)

Helm of Awakening

Exalted Flamer of Tzeentch

Sorcerous Inspiration — At the beginning of your upkeep, return an instant or sorcery card at random from your graveyard to your hand.
Fire of Tzeentch — Whenever you cast an instant or sorcery spell, Exalted Flamer of Tzeentch deals 1 damage to each opponent.

Blazemire Verge

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

Warstorm Surge

Whenever a creature you control enters, it deals damage equal to its power to any target.

Cyclonic Rift

Return target nonland permanent you don't control to its owner's hand.
Overload {6}{U} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Aggravated Assault

{3}{R}{R}: Untap all creatures you control. After this main phase, there is an additional combat phase followed by an additional main phase. Activate only as a sorcery.

Enduring Tenacity

Whenever you gain life, target opponent loses that much life.
When Enduring Tenacity dies, if it was a creature, return it to the battlefield under its owner's control. It's an enchantment. (It's not a creature.)

Command Tower

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

Burnt Offering

As an additional cost to cast this spell, sacrifice a creature.
Add X mana in any combination of {B} and/or {R}, where X is the sacrificed creature's mana value.

Heartless Summoning

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

Mystical Tutor

Search your library for an instant or sorcery card, reveal it, then shuffle and put that card on top.

Bitter Triumph

As an additional cost to cast this spell, discard a card or pay 3 life.
Destroy target creature or planeswalker.

Lord of the Void

Flying
Whenever Lord of the Void deals combat damage to a player, exile the top seven cards of that player's library, then put a creature card from among them onto the battlefield under your control.

Burning-Rune Demon

Flying
When Burning-Rune Demon enters, you may search your library for exactly two cards not named Burning-Rune Demon that have different names. If you do, reveal those cards. An opponent chooses one of them. Put the chosen card into your hand and the other into your graveyard, then shuffle.

Herald of Slaanesh

Locus of Slaanesh — Demon spells you cast cost {2} less to cast.
Other Demons you control have haste.

Untimely Malfunction

Choose one —
• Destroy target artifact.
• Change the target of target spell or ability with a single target.
• One or two target creatures can't block this turn.

Dark Ritual

Urborg, Tomb of Yawgmoth

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

Grim Hireling

Whenever one or more creatures you control deal combat damage to a player, create two Treasure tokens.
{B}, Sacrifice X Treasures: Target creature gets -X/-X until end of turn. Activate only as a sorcery.

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.

Unclaimed Territory

As Unclaimed Territory enters, choose a creature type.
{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to cast a creature spell of the chosen type.

Swamp

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.

Darkness

Prevent all combat damage that would be dealt this turn.

Varragoth, Bloodsky Sire

Deathtouch
Boast — {1}{B}: Target player searches their library for a card, then shuffles and puts that card on top. (Activate only if this creature attacked this turn and only once each turn.)

Urza's Incubator

As Urza's Incubator enters, choose a creature type.
Creature spells of the chosen type cost {2} less to cast.

Venser's Journal

You have no maximum hand size.
At the beginning of your upkeep, you gain 1 life for each card in your hand.

Basalt Monolith

Basalt Monolith doesn't untap during your untap step.
{T}: Add {C}{C}{C}.
{3}: Untap Basalt Monolith.

Mountain

Sheoldred, the Apocalypse

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

Scrawling Crawler

At the beginning of your upkeep, each player draws a card.
Whenever an opponent draws a card, that player loses 1 life.

Rite of Replication

Kicker {5} (You may pay an additional {5} as you cast this spell.)
Create a token that's a copy of target creature. If this spell was kicked, create five of those tokens instead.

Underground River

{T}: Add {C}.
{T}: Add {U} or {B}. Underground River deals 1 damage to you.

Rhystic Study

Whenever an opponent casts a spell, you may draw a card unless that player pays {1}.

Emergency Weld

Return target artifact or creature card from your graveyard to your hand. Create a 1/1 colorless Soldier artifact creature token.

Rakdos Charm

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

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.

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.

Sol Ring

Bloodstained Mire

{T}, Pay 1 life, Sacrifice Bloodstained Mire: Search your library for a Swamp or Mountain card, put it onto the battlefield, then shuffle.

Valgavoth's Lair

Hexproof
Valgavoth's Lair enters tapped. As it enters, choose a color.
{T}: Add one mana of the chosen color.

Gloomlake Verge

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

Crucible of Worlds

The Key to the Vault

Whenever equipped creature deals combat damage to a player, look at that many cards from the top of your library. You may exile a nonland card from among them. Put the rest on the bottom of your library in a random order. You may cast the exiled card without paying its mana cost.
Equip {2}{U}

Be'lakor, the Dark Master

Flying
Prince of Chaos — When Be'lakor, the Dark Master enters, you draw X cards and you lose X life, where X is the number of Demons you control.
Lord of Torment — Whenever another Demon you control enters, it deals damage equal to its power to any target.

Ritual Chamber

When you unlock this door, create a 6/6 black Demon creature token with flying.
(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.)

Unholy Annex

At the beginning of your end step, draw a card. If you control a Demon, each opponent loses 2 life and you gain 2 life. Otherwise, you lose 2 life.
(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.)

Unholy Annex // Ritual Chamber

Bolas's Citadel

You may look at the top card of your library any time.
You may play lands and cast spells from the top of your library. If you cast a spell this way, pay life equal to its mana value rather than pay its mana cost.
{T}, Sacrifice ten nonland permanents: Each opponent loses 10 life.

Tendo Ice Bridge

Tendo Ice Bridge enters with a charge counter on it.
{T}: Add {C}.
{T}, Remove a charge counter from Tendo Ice Bridge: Add one mana of any color.

Conqueror's Flail

Equipped creature gets +1/+1 for each color among permanents you control.
As long as Conqueror's Flail is attached to a creature, your opponents can't cast spells during your turn.
Equip {2}

Cabal Coffers

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

Deserted Temple

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

Demonic Counsel

Search your library for a Demon card, reveal it, put it into your hand, then shuffle.
Delirium — If there are four or more card types among cards in your graveyard, instead search your library for any card, put it into your hand, then shuffle.

Price of Glory

Whenever a player taps a land for mana, if it's not that player's turn, destroy that land.

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.

Fiery Emancipation

If a source you control would deal damage to a permanent or player, it deals triple that damage to that permanent or player instead.

Grave Pact

Whenever a creature you control dies, each other player sacrifices a creature of their choice.

Demonic Tutor

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

Whip of Erebos

Creatures you control have lifelink.
{2}{B}{B}, {T}: Return target creature card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the next end step. If it would leave the battlefield, exile it instead of putting it anywhere else. Activate only as a sorcery.

Path of Ancestry

Path of Ancestry 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.)

Chimil, the Inner Sun

Spells you control can't be countered.
At the beginning of your end step, discover 5. (Exile cards from the top of your library until you exile a nonland card with mana value 5 or less. Cast it without paying its mana cost or put it into your hand. Put the rest on the bottom in a random order.)

Crawlspace

No more than two creatures can attack you each combat.

Dread Cacodemon

When Dread Cacodemon enters, if you cast it from your hand, destroy all creatures your opponents control, then tap all other creatures you control.

Cavern of Souls

As Cavern of Souls enters, choose a creature type.
{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to cast a creature spell of the chosen type, and that spell can't be countered.

Sensei's Divining Top

{1}: Look at the top three cards of your library, then put them back in any order.
{T}: Draw a card, then put Sensei's Divining Top on top of its owner's library.

Ob Nixilis, Unshackled

Flying, trample
Whenever an opponent searches their library, that player sacrifices a creature of their choice and loses 10 life.
Whenever another creature dies, put a +1/+1 counter on Ob Nixilis, Unshackled.

Harvester of Souls

Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)
Whenever another nontoken creature dies, you may draw a card.

Feed the Swarm

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

Field of Ruin

{T}: Add {C}.
{2}, {T}, Sacrifice Field of Ruin: Destroy target nonbasic land an opponent controls. Each player searches their library for a basic land card, puts it onto the battlefield, then shuffles.

Enduring Courage

Whenever another creature you control enters, it gets +2/+0 and gains haste until end of turn.
When Enduring Courage dies, if it was a creature, return it to the battlefield under its owner's control. It's an enchantment. (It's not a creature.)