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.

Sol Ring

Polluted Delta

{T}, Pay 1 life, Sacrifice this land: Search your library for an Island or Swamp card, put it onto the battlefield, then shuffle.

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.)

Cavern of Souls

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, and that spell can't be countered.

Liliana's Contract

When this enchantment 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.

Rhystic Study

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

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.

Spinerock Knoll

Hideaway 4 (When this land enters, look at the top four cards of your library, exile one face down, then put the rest on the bottom in a random order.)
This land enters tapped.
{T}: Add {R}.
{R}, {T}: You may play the exiled card without paying its mana cost if an opponent was dealt 7 or more damage this turn.

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.)

Rune-Scarred Demon

Flying
When this creature enters, search your library for a card, put it into your hand, then shuffle.

Urborg, Tomb of Yawgmoth

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

Nexus of Fate

Take an extra turn after this one.
If Nexus of Fate would be put into a graveyard from anywhere, reveal Nexus of Fate and shuffle it into its owner's library instead.

Plague Drone

Flying
Rot Fly — If an opponent would gain life, that player loses that much life instead.

Urza's Incubator

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

Thespian's Stage

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

Bloodstained Mire

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

Rakdos, the Showstopper

Flying, trample
When Rakdos enters, flip a coin for each creature that isn't a Demon, Devil, or Imp. Destroy each creature whose coin comes up tails.

Ancient Tomb

{T}: Add {C}{C}. This land deals 2 damage to you.

Lord of Change

Flying, ward {3}
Architect of Deception — When this creature enters, draw three cards.

Crumbling Necropolis

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

Temple of the False God

{T}: Add {C}{C}. Activate only if you control five or more lands.

Lord Xander, the Collector

When Lord Xander enters, target opponent discards half the cards in their hand, rounded down.
Whenever Lord Xander attacks, defending player mills half their library, rounded down.
When Lord Xander dies, target opponent sacrifices half the nonland permanents they control of their choice, rounded down.

Xander's Lounge

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

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.

Watery Grave

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

Reflecting Pool

{T}: Add one mana of any type that a land you control could produce.

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.

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.

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.

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.)

Demonic Collusion

Buyback—Discard two cards. (You may discard two cards in addition to any other costs as you cast this spell. If you do, put this card into your hand as it resolves.)
Search your library for a card, put that card into your hand, then shuffle.

Blood Crypt

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

Strip Mine

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

Mortuary Mire

This land enters tapped.
When this land enters, you may put target creature card from your graveyard on top of your library.
{T}: Add {B}.

Underground River

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

City of Brass

Whenever this land becomes tapped, it deals 1 damage to you.
{T}: Add one mana of any color.

Swamp

Island

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 and draw a card.

Arcane Signet

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

Exotic Orchard

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

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.

Panharmonicon

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

Scalding Tarn

{T}, Pay 1 life, Sacrifice this land: Search your library for an Island or Mountain card, put it onto the battlefield, then shuffle.

Dark Ritual

Reflections of Littjara

As this enchantment enters, choose a creature type.
Whenever you cast a spell of the chosen type, copy that spell. (A copy of a permanent spell becomes a token.)

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, this creature deals 1 damage to each opponent.

Shivan Reef

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

Time Warp

Target player takes an extra turn after this one.

Heralds of Tzeentch

Flying
Cascade (When you cast this spell, exile cards from the top of your library until you exile a nonland card that costs less. You may cast it without paying its mana cost. Put the exiled cards on the bottom in a random order.)

Demonic Gifts

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

Steam Vents

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

Dream Devourer

Each nonland card in your hand without foretell has foretell. Its foretell cost is equal to its mana cost reduced by {2}. (During your turn, you may pay {2} and exile it from your hand face down. Cast it on a later turn for its foretell cost.)
Whenever you foretell a card, this creature gets +2/+0 until end of turn.

Mountain

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.

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.)

Burning-Rune Demon

Flying
When this creature 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.

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.

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.)

Blasphemous Act

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

Roaming Throne

Ward {2}
As this creature enters, choose a creature type.
This creature is the chosen type in addition to its other types.
If a triggered ability of another creature you control of the chosen type triggers, it triggers an additional time.

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.

Sheoldred, the Apocalypse

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

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.

Maze of Ith

{T}: Untap target attacking creature. Prevent all combat damage that would be dealt to and dealt by that creature this turn.

Séance Board

Morbid — At the beginning of each end step, if a creature died this turn, put a soul counter on this artifact.
{T}: Add X mana of any one color, where X is the number of soul counters on this artifact. Spend this mana only to cast instant, sorcery, Demon, and Spirit spells.

Bloodcrusher of Khorne

Trample
Devastating Charge — Other creatures you control have trample.

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.)

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.)

Reanimate

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

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!

Kindred Dominance

Choose a creature type. Destroy all creatures that aren't of the chosen type.

Vampiric Tutor

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

Rakdos, Patron of Chaos

Flying, trample
At the beginning of your end step, target opponent may sacrifice two nonland, nontoken permanents of their choice. If they don't, you draw two cards.

Command Tower

Heartless Summoning

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

Drowned Catacomb

This land enters tapped unless you control an Island or a Swamp.
{T}: Add {U} or {B}.

Damnation

Destroy all creatures. They can't be regenerated.

Deadly Rollick

If you control a commander, you may cast this spell without paying its mana cost.
Exile target creature.

Sulfurous Springs

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

Havoc Festival

Players can't gain life.
At the beginning of each player's upkeep, that player loses half their life, rounded up.

Culling the Weak

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

Nightscape Familiar

Blue spells and red spells you cast cost {1} less to cast.
{1}{B}: Regenerate this creature.

Demonic Tutor

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

Dragonskull Summit

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

Grievous Wound

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

Lord of the Forsaken

Flying, trample
{B}, Sacrifice another creature: Target player mills three cards.
Pay 1 life: Add {C}. Spend this mana only to cast a spell from your graveyard.

Sneak Attack

{R}: You may put a creature card from your hand onto the battlefield. That creature gains haste. Sacrifice the creature at the beginning of the next end step.

Sulfur Falls

This land enters tapped unless you control an Island or a Mountain.
{T}: Add {U} or {R}.

Raphael, Fiendish Savior

Flying
Other Demons, Devils, Imps, and Tieflings you control get +1/+1 and have lifelink.
At the beginning of each end step, if a creature card was put into your graveyard from anywhere this turn, create a 1/1 red Devil creature token with "When this token dies, it deals 1 damage to any target."

Scourge of the Skyclaves

Kicker {4}{B}
When you cast this spell, if it was kicked, each player loses half their life, rounded up.
Scourge of the Skyclaves's power and toughness are each equal to 20 minus the highest life total among players.

Mana Drain

Counter target spell. At the beginning of your next main phase, add an amount of {C} equal to that spell's mana value.

Herald of Slaanesh

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

Counterspell

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.