When Abhorrent Overlord enters the battlefield, create a number of 1/1 black Harpy creature tokens with flying equal to your devotion to black. (Each {B} in the mana costs of permanents you control counts toward your devotion to black.)
At the beginning of your upkeep, sacrifice a creature.
6 /
6
{3}{B}
Accursed Witch
Creature - Human Shaman
Spells your opponents cast that target Accursed Witch cost {1} less to cast.
When Accursed Witch dies, return it to the battlefield transformed under your control attached to target opponent.
4 /
2
--
Infectious Curse
Enchantment - Aura Curse
Enchant player
Spells you cast that target enchanted player cost {1} less to cast.
At the beginning of enchanted player's upkeep, that player loses 1 life and you gain 1 life.
4 /
2
--
Akoum Refuge
Land
Akoum Refuge enters the battlefield tapped.
When Akoum Refuge enters the battlefield, you gain 1 life.
{T}: Add {B} or {R}.
{2}
Arcane Signet
Artifact
{T}: Add one mana of any color in your commander's color identity.
{3}{B}{B}
Archfiend of Depravity
Creature - Demon
Flying
At the beginning of each opponent's end step, that player chooses up to two creatures they control, then sacrifices the rest.
5 /
4
{B}{B}{R}
Bedevil
Instant
Destroy target artifact, creature, or planeswalker.
{4}{B}
Bitterheart Witch
Creature - Human Shaman
Deathtouch
When Bitterheart Witch dies, you may search your library for a Curse card, put it onto the battlefield attached to target player, then shuffle.
1 /
2
--
Blackcleave Cliffs
Land
Blackcleave Cliffs enters the battlefield tapped unless you control two or fewer other lands.
{T}: Add {B} or {R}.
--
Blightstep Pathway
Land
{T}: Add {B}.
--
Searstep Pathway
Land
{T}: Add {R}.
--
Blood Crypt
Land - Swamp Mountain
({T}: Add {B} or {R}.)
As Blood Crypt enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.
{3}{B}
Blood Reckoning
Enchantment
Whenever a creature attacks you or a planeswalker you control, that creature's controller loses 1 life.
--
Bloodfell Caves
Land
Bloodfell Caves enters the battlefield tapped.
When Bloodfell Caves enters the battlefield, you gain 1 life.
{T}: Add {B} or {R}.
{3}{B}{B}
Bloodgift Demon
Creature - Demon
Flying
At the beginning of your upkeep, target player draws a card and loses 1 life.
5 /
4
--
Bloodstained Mire
Land
{T}, Pay 1 life, Sacrifice Bloodstained Mire: Search your library for a Swamp or Mountain card, put it onto the battlefield, then shuffle.
--
Canyon Slough
Land - Swamp Mountain
({T}: Add {B} or {R}.)
Canyon Slough enters the battlefield tapped.
Cycling {2} ({2}, Discard this card: Draw a card.)
--
Castle Locthwain
Land
Castle Locthwain enters the battlefield tapped unless you control a Swamp.
{T}: Add {B}.
{1}{B}{B}, {T}: Draw a card, then you lose life equal to the number of cards in your hand.
--
Cinder Barrens
Land
Cinder Barrens enters the battlefield tapped.
{T}: Add {B} or {R}.
--
Command Tower
Land
{T}: Add one mana of any color in your commander's color identity.
{5}{B}{B}
Cruel Reality
Enchantment - Aura Curse
Enchant player
At the beginning of enchanted player's upkeep, that player sacrifices a creature or planeswalker. If the player can't, they lose 5 life.
{3}{B}
Crypt Ghast
Creature - Spirit
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}.
2 /
2
{3}{R}{R}
Curse of Bloodletting
Enchantment - Aura Curse
Enchant player
If a source would deal damage to enchanted player, it deals double that damage to that player instead.
{3}{B}{B}
Curse of Death's Hold
Enchantment - Aura Curse
Enchant player
Creatures enchanted player controls get -1/-1.
{2}{R}
Curse of Hospitality
Enchantment - Aura Curse
Enchant player
Creatures attacking enchanted player have trample.
Whenever a creature deals combat damage to enchanted player, that player exiles the top card of their library. Until end of turn, that creature's controller may play that card and they may spend mana as though it were mana of any color to cast that spell.
{4}{B}
Curse of Misfortunes
Enchantment - Aura Curse
Enchant player
At the beginning of your upkeep, you may search your library for a Curse card that doesn't have the same name as a Curse attached to enchanted player, put it onto the battlefield attached to that player, then shuffle.
{2}{B}
Curse of Shallow Graves
Enchantment - Aura Curse
Enchant player
Whenever a player attacks enchanted player with one or more creatures, that attacking player may create a tapped 2/2 black Zombie creature token.
{1}{R}
Curse of Stalked Prey
Enchantment - Aura Curse
Enchant player
Whenever a creature deals combat damage to enchanted player, put a +1/+1 counter on that creature.
{4}{B}
Curse of Thirst
Enchantment - Aura Curse
Enchant player
At the beginning of enchanted player's upkeep, Curse of Thirst deals damage to that player equal to the number of Curses attached to them.
{2}{R}
Curse of the Nightly Hunt
Enchantment - Aura Curse
Enchant player
Creatures enchanted player controls attack each combat if able.
{2}{B}{B}
Damnation
Sorcery
Destroy all creatures. They can't be regenerated.
{3}{B}{B}
Demon of Wailing Agonies
Creature - Demon
Flying
Lieutenant -- As long as you control your commander, Demon of Wailing Agonies gets +2/+2 and has "Whenever Demon of Wailing Agonies deals combat damage to a player, that player sacrifices a creature."
4 /
4
{4}{B}{B}
Demonlord Belzenlok
Legendary Creature - Elder Demon
Flying, trample
When Demonlord Belzenlok enters the battlefield, 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.
6 /
6
{2}{B}{B}
Desecration Demon
Creature - Demon
Flying
At the beginning of each combat, any opponent may sacrifice a creature. If a player does, tap Desecration Demon and put a +1/+1 counter on it.
6 /
6
--
Dragonskull Summit
Land
Dragonskull Summit enters the battlefield tapped unless you control a Swamp or a Mountain.
{T}: Add {B} or {R}.
{B}{R}
Dreadbore
Sorcery
Destroy target creature or planeswalker.
--
Drossforge Bridge
Artifact Land
Drossforge Bridge enters the battlefield tapped.
Indestructible
{T}: Add {B} or {R}.
{1}{B}{B}
Embodiment of Agonies
Creature - Demon
Flying, deathtouch
Embodiment of Agonies enters the battlefield with a +1/+1 counter on it for each different mana cost among nonland cards in your graveyard. (For example, {2}{B} and {1}{B}{B} are different mana costs.)
0 /
0
{4}{B}{B}
Feaster of Fools
Creature - Demon
Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for {1} or one mana of that creature's color.)
Flying
Devour 2 (As this enters the battlefield, you may sacrifice any number of creatures. This creature enters the battlefield with twice that many +1/+1 counters on it.)
3 /
3
--
Foreboding Ruins
Land
As Foreboding Ruins enters the battlefield, you may reveal a Swamp or Mountain card from your hand. If you don't, Foreboding Ruins enters the battlefield tapped.
{T}: Add {B} or {R}.
{3}{B}{B}
Fraying Omnipotence
Sorcery
Each player loses half their life, then discards half the cards in their hand, then sacrifices half the creatures they control. Round up each time.
--
Geothermal Bog
Land - Swamp Mountain
({T}: Add {B} or {R}.)
Geothermal Bog enters the battlefield tapped.
{4}{B}{B}
Harvester of Souls
Creature - Demon
Deathtouch
Whenever another nontoken creature dies, you may draw a card.
5 /
5
--
Haunted Ridge
Land
Haunted Ridge enters the battlefield tapped unless you control two or more other lands.
{T}: Add {B} or {R}.
{1}{B}{B}
Hero's Downfall
Instant
Destroy target creature or planeswalker.
--
Immersturm Skullcairn
Land
Immersturm Skullcairn enters the battlefield tapped.
{T}: Add {B}.
{1}{B}{R}{R}, {T}, Sacrifice Immersturm Skullcairn: It deals 3 damage to target player. That player discards a card. Activate only as a sorcery.
{3}{B}{B}
Indulgent Tormentor
Creature - Demon
Flying
At the beginning of your upkeep, draw a card unless target opponent sacrifices a creature or pays 3 life.
5 /
3
{2}{B}{R}
Kardur, Doomscourge
Legendary Creature - Demon Berserker
When Kardur, Doomscourge enters the battlefield, until your next turn, creatures your opponents control attack each combat if able and attack a player other than you if able.
Whenever an attacking creature dies, each opponent loses 1 life and you gain 1 life.
4 /
3
{4}{B}{B}
Kothophed, Soul Hoarder
Legendary Creature - Demon
Flying
Whenever a permanent owned by another player is put into a graveyard from the battlefield, you draw a card and you lose 1 life.
6 /
6
{3}{B}{B}
Liliana's Contract
Enchantment
When Liliana's Contract enters the battlefield, 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.
{2}{B}{B}{R}{R}
Malfegor
Legendary Creature - Demon Dragon
Flying
When Malfegor enters the battlefield, discard your hand. Each opponent sacrifices a creature for each card discarded this way.
6 /
6
{3}{B}{R}
Master of Cruelties
Creature - Demon
First strike, deathtouch
Master of Cruelties can only attack alone.
Whenever Master of Cruelties attacks a player and isn't blocked, that player's life total becomes 1. Master of Cruelties assigns no combat damage this combat.
1 /
4
{2}{B}{B}
Mindwrack Demon
Creature - Demon
Flying, trample
When Mindwrack Demon enters the battlefield, mill four cards.
Delirium -- At the beginning of your upkeep, you lose 4 life unless there are four or more card types among cards in your graveyard.
4 /
5
--
Mortuary Mire
Land
Mortuary Mire enters the battlefield tapped.
When Mortuary Mire enters the battlefield, you may put target creature card from your graveyard on top of your library.
{T}: Add {B}.
--
Mountain
Basic Land - Mountain
({T}: Add {R}.)
--
Mountain
Basic Land - Mountain
({T}: Add {R}.)
--
Mountain
Basic Land - Mountain
({T}: Add {R}.)
{1}{B}{B}
Murder
Instant
Destroy target creature.
{5}{B}
Netherborn Phalanx
Creature - Horror
When Netherborn Phalanx enters the battlefield, each opponent loses 1 life for each creature they control.
Transmute {1}{B}{B} ({1}{B}{B}, Discard this card: Search your library for a card with the same mana value as this card, reveal it, put it into your hand, then then shuffle. Transmute only as a sorcery.)
2 /
4
{3}{B}{B}
Ob Nixilis Reignited
Legendary Planeswalker - Nixilis
+1: You draw a card and you lose 1 life.
-3: Destroy target creature.
-8: Target opponent gets an emblem with "Whenever a player draws a card, you lose 2 life."
L:
5
{3}{B}{B}
Ob Nixilis of the Black Oath
Legendary Planeswalker - Nixilis
+2: Each opponent loses 1 life. You gain life equal to the life lost this way.
-2: Create a 5/5 black Demon creature token with flying. You lose 2 life.
-8: You get an emblem with "{1}{B}, Sacrifice a creature: You gain X life and draw X cards, where X is the sacrificed creature's power."
Ob Nixilis of the Black Oath can be your commander.
L:
3
{4}{B}{B}
Ob Nixilis, Unshackled
Legendary Creature - Demon
Flying, trample
Whenever an opponent searches their library, that player sacrifices a creature and loses 10 life.
Whenever another creature dies, put a +1/+1 counter on Ob Nixilis, Unshackled.
4 /
4
{3}{B}{B}
Ob Nixilis, the Fallen
Legendary Creature - Demon
Landfall -- Whenever a land enters the battlefield under your control, you may have target player lose 3 life. If you do, put three +1/+1 counters on Ob Nixilis, the Fallen.
3 /
3
{3}{B}{B}
Ob Nixilis, the Hate-Twisted
Legendary Planeswalker - Nixilis
Whenever an opponent draws a card, Ob Nixilis, the Hate-Twisted deals 1 damage to that player.
-2: Destroy target creature. Its controller draws two cards.
L:
5
{B}{R}
Rakdos Charm
Instant
Choose one --
• Exile target player's graveyard.
• Destroy target artifact.
• Each creature deals 1 damage to its controller.
--
Rakdos Guildgate
Land - Gate
Rakdos Guildgate enters the battlefield tapped.
{T}: Add {B} or {R}.
{3}
Rakdos Locket
Artifact
{T}: Add {B} or {R}.
{B/R}{B/R}{B/R}{B/R}, {T}, Sacrifice Rakdos Locket: Draw two cards.
{2}
Rakdos Signet
Artifact
{1}, {T}: Add {B}{R}.
{2}{B}{B}{R}{R}
Rakdos the Defiler
Legendary Creature - Demon
Flying, trample
Whenever Rakdos the Defiler attacks, sacrifice half the non-Demon permanents you control, rounded up.
Whenever Rakdos deals combat damage to a player, that player sacrifices half the non-Demon permanents they control, rounded up.
7 /
6
{X}{B}{R}
Rakdos's Return
Sorcery
Rakdos's Return deals X damage to target opponent or planeswalker. That player or that planeswalker's controller discards X cards.
{B}{B}{R}{R}
Rakdos, Lord of Riots
Legendary Creature - Demon
You can't cast this spell unless an opponent lost life this turn.
Flying, trample
Creature spells you cast cost {1} less to cast for each 1 life your opponents have lost this turn.
6 /
6
{4}{B}{R}
Rakdos, the Showstopper
Legendary Creature - Demon
Flying, trample
When Rakdos, the Showstopper enters the battlefield, flip a coin for each creature that isn't a Demon, Devil, or Imp. Destroy each creature whose coin comes up tails.
6 /
6
{5}{B}{B}{B}
Razaketh, the Foulblooded
Legendary Creature - Demon
Flying, trample
Pay 2 life, Sacrifice another creature: Search your library for a card, put that card into your hand, then shuffle.
8 /
8
{3}{B}{B}{B}
Reaper from the Abyss
Creature - Demon
Flying
Morbid -- At the beginning of each end step, if a creature died this turn, destroy target non-Demon creature.
6 /
6
{4}{B}{B}{B}{B}
Reiver Demon
Creature - Demon
Flying
When Reiver Demon enters the battlefield, if you cast it from your hand, destroy all nonartifact, nonblack creatures. They can't be regenerated.
6 /
6
{3}{B}{B}
Remorseless Punishment
Sorcery
Target opponent loses 5 life unless that player discards two cards or sacrifices a creature or planeswalker. Repeat this process once.
{3}{B}
Revenge of Ravens
Enchantment
Whenever a creature attacks you or a planeswalker you control, that creature's controller loses 1 life and you gain 1 life.
{5}{B}{B}
Rune-Scarred Demon
Creature - Demon
Flying
When Rune-Scarred Demon enters the battlefield, search your library for a card, put it into your hand, then shuffle.
6 /
6
--
Smoldering Marsh
Land - Swamp Mountain
({T}: Add {B} or {R}.)
Smoldering Marsh enters the battlefield tapped unless you control two or more basic lands.
{1}
Sol Ring
Artifact
{T}: Add {C}{C}.
--
Stensia Bloodhall
Land
{T}: Add {C}.
{3}{B}{R}, {T}: Stensia Bloodhall deals 2 damage to target player or planeswalker.
--
Sulfurous Mire
Snow Land - Swamp Mountain
({T}: Add {B} or {R}.)
Sulfurous Mire enters the battlefield tapped.
--
Sulfurous Springs
Land
{T}: Add {C}.
{T}: Add {B} or {R}. Sulfurous Springs deals 1 damage to you.
--
Swamp
Basic Land - Swamp
({T}: Add {B}.)
--
Swamp
Basic Land - Swamp
({T}: Add {B}.)
--
Swamp
Basic Land - Swamp
({T}: Add {B}.)
--
Swamp
Basic Land - Swamp
({T}: Add {B}.)
--
Swamp
Basic Land - Swamp
({T}: Add {B}.)
--
Swamp
Basic Land - Swamp
({T}: Add {B}.)
--
Swamp
Basic Land - Swamp
({T}: Add {B}.)
--
Tainted Peak
Land
{T}: Add {C}.
{T}: Add {B} or {R}. Activate only if you control a Swamp.
--
Temple of Malice
Land
Temple of Malice enters the battlefield tapped.
When Temple of Malice enters the battlefield, scry 1.
{T}: Add {B} or {R}.
{B}{R}
Terminate
Instant
Destroy target creature. It can't be regenerated.
{6}{B}{B}
Torgaar, Famine Incarnate
Legendary Creature - Avatar
As an additional cost to cast this spell, you may sacrifice any number of creatures. This spell costs {2} less to cast for each creature sacrificed this way.
When Torgaar, Famine Incarnate enters the battlefield, up to one target player's life total becomes half their starting life total, rounded down.
7 /
6
{3}{B}
Torment of Scarabs
Enchantment - Aura Curse
Enchant player
At the beginning of enchanted player's upkeep, that player loses 3 life unless they sacrifice a nonland permanent or discard a card.
{1}{B}
Trespasser's Curse
Enchantment - Aura Curse
Enchant player
Whenever a creature enters the battlefield under enchanted player's control, that player loses 1 life and you gain 1 life.
{1}{B}{R}
Unlicensed Disintegration
Instant
Destroy target creature. If you control an artifact, Unlicensed Disintegration deals 3 damage to that creature's controller.
{5}{B}{B}{B}
Vilis, Broker of Blood
Legendary Creature - Demon
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.)
8 /
8
{2}{R}
Vow of Lightning
Enchantment - Aura
Enchant creature
Enchanted creature gets +2/+2, has first strike, and can't attack you or planeswalkers you control.
{2}{B}
Vow of Torment
Enchantment - Aura
Enchant creature
Enchanted creature gets +2/+2, has menace, and can't attack you or planeswalkers you control. (It can't be blocked except by two or more creatures.)
--
Westvale Abbey
Land
{T}: Add {C}.
{5}, {T}, Pay 1 life: Create a 1/1 white and black Human Cleric creature token.
{5}, {T}, Sacrifice five creatures: Transform Westvale Abbey, then untap it.
--
Ormendahl, Profane Prince
Legendary Creature - Demon
Flying, lifelink, indestructible, haste
--
Witch's Cottage
Land - Swamp
({T}: Add {B}.)
Witch's Cottage enters the battlefield tapped unless you control three or more other Swamps.
When Witch's Cottage enters the battlefield untapped, you may put target creature card from your graveyard on top of your library.