You can't win the game and your opponents can't lose the game.
6 /
6
{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
{4}
Assault Suit
Artifact - Equipment
Equipped creature gets +2/+2, has haste, can't attack you or planeswalkers you control, and can't be sacrificed.
At the beginning of each opponent's upkeep, you may have that player gain control of equipped creature until end of turn. If you do, untap it.
Equip {3}
{3}{B}
Bite of the Black Rose
Sorcery
Will of the council -- Starting with you, each player votes for sickness or psychosis. If sickness gets more votes, creatures your opponents control get -2/-2 until end of turn. If psychosis gets more votes or the vote is tied, each opponent discards two cards.
{1}{B}{B}
Blanket of Night
Enchantment
Each land is a Swamp in addition to its other land types.
{3}{B}
Blood Speaker
Creature - Ogre Shaman
At the beginning of your upkeep, you may sacrifice Blood Speaker. If you do, search your library for a Demon card, reveal that card, put it into your hand, then shuffle.
Whenever a Demon enters the battlefield under your control, return Blood Speaker from your graveyard to your hand.
3 /
2
{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
{4}{B}{B}
Bloodsoaked Altar
Artifact
{T}, Pay 2 life, Discard a card, Sacrifice a creature: Create a 5/5 black Demon creature token with flying. Activate only as a sorcery.
{3}
Bontu's Monument
Legendary Artifact
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.
{4}{B}{B}
Burning-Rune Demon
Creature - Demon Berserker
Flying
When Burning-Rune Demon enters the battlefield, 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.
6 /
6
--
Cabal Coffers
Land
{2}, {T}: Add {B} for each Swamp you control.
--
Cabal Stronghold
Land
{T}: Add {C}.
{3}, {T}: Add {B} for each basic Swamp you control.
{6}
Caged Sun
Artifact
As Caged Sun enters the battlefield, 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.
{4}{B}{B}
Capital Punishment
Sorcery
Council's dilemma -- Starting with you, each player votes for death or taxes. Each opponent sacrifices a creature for each death vote and discards a card for each taxes vote.
{2}{B}{B}
Demon of Catastrophes
Creature - Demon
As an additional cost to cast this spell, sacrifice a creature.
Flying, trample
6 /
6
{6}{B}{B}{B}
Demon of Death's Gate
Creature - Demon
You may pay 6 life and sacrifice three black creatures rather than pay this spell's mana cost.
Flying, trample
9 /
9
{5}{B}{B}
Demon of Loathing
Creature - Demon
Flying, trample
Whenever Demon of Loathing deals combat damage to a player, that player sacrifices a creature.
7 /
7
{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
{3}{B}{B}
Doom Whisperer
Creature - Nightmare Demon
Flying, trample
Pay 2 life: Surveil 2. (Look at the top two cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)
6 /
6
{5}{B}{B}
Dreadfeast Demon
Creature - Demon
Flying
At the beginning of your end step, sacrifice a non-Demon creature. If you do, create a token that's a copy of Dreadfeast Demon.
6 /
6
{1}{B}
Dreadhorde Invasion
Enchantment
At the beginning of your upkeep, you lose 1 life and amass Zombies 1. (Put a +1/+1 counter on an Army you control. It's also a Zombie. If you don't control an Army, create a 0/0 black Zombie Army creature token first.)
Whenever a Zombie token you control with power 6 or greater attacks, it gains lifelink until end of turn.
{3}
Druidic Satchel
Artifact
{2}, {T}: Reveal the top card of your library. If it's a creature card, create a 1/1 green Saproling creature token. If it's a land card, put that card onto the battlefield under your control. If it's a noncreature, nonland card, you gain 2 life.
{7}
Elbrus, the Binding Blade
Legendary Artifact - Equipment
Equipped creature gets +1/+0.
When equipped creature deals combat damage to a player, unattach Elbrus, the Binding Blade, then transform it.
Equip {1}
--
Withengar Unbound
Legendary Creature - Demon
Flying, intimidate, trample (A creature with intimidate can't be blocked except by artifact creatures and/or creatures that share a color with it.)
Whenever a player loses the game, put thirteen +1/+1 counters on Withengar Unbound.
{1}
Expedition Map
Artifact
{2}, {T}, Sacrifice Expedition Map: Search your library for a land card, reveal it, put it into your hand, then shuffle.
{5}
Gauntlet of Power
Artifact
As Gauntlet of Power enters the battlefield, choose a color.
Creatures of the chosen color get +1/+1.
Whenever a basic land is tapped for mana of the chosen color, its controller adds an additional one mana of that color.
{3}
Herald's Horn
Artifact
As Herald's Horn enters the battlefield, choose a creature type.
Creature spells you cast of the chosen type cost {1} less to cast.
At the beginning of your upkeep, look at the top card of your library. If it's a creature card of the chosen type, you may reveal it and put it into your hand.
{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
{4}{B}
Infernal Offering
Sorcery
Choose an opponent. You and that player each sacrifice a creature. Each player who sacrificed a creature this way draws two cards.
Choose an opponent. Return a creature card from your graveyard to the battlefield, then that player returns a creature card from their graveyard to the battlefield.
{2}
Jet Medallion
Artifact
Black spells you cast cost {1} less to cast.
{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
{4}
Lashwrithe
Artifact - Equipment
Living weapon (When this Equipment enters the battlefield, create a 0/0 black Phyrexian Germ creature token, then attach this to it.)
Equipped creature gets +1/+1 for each Swamp you control.
Equip {B/P}{B/P} ({B/P} can be paid with either {B} or 2 life.)
--
Leechridden Swamp
Land - Swamp
({T}: Add {B}.)
Leechridden Swamp enters the battlefield tapped.
{B}, {T}: Each opponent loses 1 life. Activate only if you control two or more black permanents.
{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.
{4}{B}{B}
Lord of the Forsaken
Creature - Demon
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.
6 /
6
{4}{B}{B}{B}
Lord of the Void
Creature - Demon
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.
7 /
7
{3}
Manascape Refractor
Artifact
Manascape Refractor enters the battlefield tapped.
Manascape Refractor has all activated abilities of all lands on the battlefield.
You may spend mana as though it were mana of any color to pay the activation costs of Manascape Refractor's abilities.
--
Memorial to Folly
Land
Memorial to Folly enters the battlefield tapped.
{T}: Add {B}.
{2}{B}, {T}, Sacrifice Memorial to Folly: Return target creature card from your graveyard to your hand.
--
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}.
--
Myriad Landscape
Land
Myriad Landscape enters the battlefield tapped.
{T}: Add {C}.
{2}, {T}, Sacrifice Myriad Landscape: Search your library for up to two basic land cards that share a land type, put them onto the battlefield tapped, then shuffle.
{4}
Nightmare Lash
Artifact - Equipment
Equipped creature gets +1/+1 for each Swamp you control.
Equip--Pay 3 life. (Pay 3 life: Attach to target creature you control. Equip only as a sorcery. This card enters the battlefield unattached and stays on the battlefield if the creature leaves.)
--
Nykthos, Shrine to Nyx
Legendary Land
{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.)
{4}
Nyx Lotus
Legendary Artifact
Nyx Lotus enters the battlefield tapped.
{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.)
{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
{5}{B}{B}
Overseer of the Damned
Creature - Demon
Flying
When Overseer of the Damned enters the battlefield, you may destroy target creature.
Whenever a nontoken creature an opponent controls dies, create a tapped 2/2 black Zombie creature token.
5 /
5
{2}{B}{B}{B}
Promise of Power
Sorcery
Choose one --
• You draw five cards and you lose 5 life.
• Create an X/X black Demon creature token with flying, where X is the number of cards in your hand.
Entwine {4} (Choose both if you pay the entwine cost.)
{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}
Reign of the Pit
Sorcery
Each player sacrifices a creature. Create an X/X black Demon creature token with flying, where X is the total power of the creatures sacrificed this way.
{2}{B}{B}
Rite of Belzenlok
Enchantment - Saga
(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I, II -- Create two 0/1 black Cleric creature tokens.
III -- Create a 6/6 black Demon creature token with flying, trample, and "At the beginning of your upkeep, sacrifice another creature. If you can't, this creature deals 6 damage to you."
{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
{B}
Scheming Symmetry
Sorcery
Choose two target players. Each of them searches their library for a card, then shuffles and puts that card on top.
{3}{B}{B}
Seizan, Perverter of Truth
Legendary Creature - Demon Spirit
At the beginning of each player's upkeep, that player loses 2 life and draws two cards.
6 /
5
{1}{B}
Skirsdag High Priest
Creature - Human Cleric
Morbid -- {T}, Tap two untapped creatures you control: Create a 5/5 black Demon creature token with flying. Activate only if a creature died this turn.
1 /
2
{3}
Strata Scythe
Artifact - Equipment
Imprint -- When Strata Scythe enters the battlefield, search your library for a land card, exile it, then shuffle.
Equipped creature gets +1/+1 for each land on the battlefield with the same name as the exiled card.
Equip {3}
--
Subterranean Hangar
Land
Subterranean Hangar enters the battlefield tapped.
{T}: Put a storage counter on Subterranean Hangar.
{T}, Remove any number of storage counters from Subterranean Hangar: Add {B} for each storage counter removed this way.
--
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}.)
--
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}.)
--
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}.)
--
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}.)
--
Swamp
Basic Land - Swamp
({T}: Add {B}.)
{2}
Sword of the Animist
Legendary Artifact - Equipment
Equipped creature gets +1/+1.
Whenever equipped creature attacks, you may search your library for a basic land card, put it onto the battlefield tapped, then shuffle.
Equip {2}
{4}{B}
Tempt with Immortality
Sorcery
Tempting offer -- Return a creature card from your graveyard to the battlefield. Each opponent may return a creature card from their graveyard to the battlefield. For each opponent who does, return a creature card from your graveyard to the battlefield.
{4}
Tempting Contract
Artifact
At the beginning of your upkeep, each opponent may create a Treasure token. For each opponent who does, you create a Treasure token.
--
Thespian's Stage
Land
{T}: Add {C}.
{2}, {T}: Thespian's Stage becomes a copy of target land, except it has this ability.
--
Tomb of Urami
Legendary Land
{T}: Add {B}. Tomb of Urami deals 1 damage to you if you don't control an Ogre.
{2}{B}{B}, {T}, Sacrifice all lands you control: Create Urami, a legendary 5/5 black Demon Spirit creature token with flying.
{1}{B}
Tyrant's Choice
Sorcery
Will of the council -- Starting with you, each player votes for death or torture. If death gets more votes, each opponent sacrifices a creature. If torture gets more votes or the vote is tied, each opponent loses 4 life.
--
Urborg, Tomb of Yawgmoth
Legendary Land
Each land is a Swamp in addition to its other land types.
{3}
Urza's Incubator
Artifact
As Urza's Incubator enters the battlefield, choose a creature type.
Creature spells of the chosen type cost {2} less to cast.
{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}{B}
Virtus's Maneuver
Sorcery
For each player, choose friend or foe. Each friend returns a creature card from their graveyard to their hand. Each foe sacrifices a creature they control.
{2}{B}
Vow of Malice
Enchantment - Aura
Enchant creature
Enchanted creature gets +2/+2, has intimidate, and can't attack you or planeswalkers you control. (A creature with intimidate can't be blocked except by artifact creatures and/or creatures that share a color with it.)
{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.
{3}{B}{B}{B}
Xathrid Demon
Creature - Demon
Flying, trample
At the beginning of your upkeep, sacrifice a creature other than Xathrid Demon, then each opponent loses life equal to the sacrificed creature's power. If you can't sacrifice a creature, tap Xathrid Demon and you lose 7 life.
7 /
7
--
Cleric
Token Creature - Cleric
Black
0 /
1
--
Cleric
Token Creature - Cleric
Black
0 /
1
--
Copy
Token
Colorless
(This token can be used to represent a token that's a copy of a permanent.)
--
Copy
Token
Colorless
(This token can be used to represent a token that's a copy of a permanent.)
--
Copy
Token
Colorless
(This token can be used to represent a token that's a copy of a permanent.)
--
Copy
Token
Colorless
(This token can be used to represent a token that's a copy of a permanent.)
--
Demon
Token Creature - Demon
Black
Flying
5 /
5
--
Demon
Token Creature - Demon
Black
Flying
5 /
5
--
Demon
Token Creature - Demon
Black
Flying
* /
*
--
Demon
Token Creature - Demon
Black
Flying, trample
At the beginning of your upkeep, sacrifice another creature. If you can't, this creature deals 6 damage to you.
6 /
6
--
Demon
Token Creature - Demon
Black
Flying
* /
*
--
Demon
Token Creature - Demon
Black
Flying
5 /
5
--
Demon
Token Creature - Demon
Black
Flying
5 /
5
--
Germ
Token Creature - Germ
Black
0 /
0
--
Human Cleric
Token Creature - Human Cleric
White, Black
1 /
1
--
Human Cleric
Token Creature - Human Cleric
White, Black
1 /
1
--
Human Cleric
Token Creature - Human Cleric
White, Black
1 /
1
--
Human Cleric
Token Creature - Human Cleric
White, Black
1 /
1
--
Saproling
Token Creature - Saproling
Green
1 /
1
--
Saproling
Token Creature - Saproling
Green
1 /
1
--
Saproling
Token Creature - Saproling
Green
1 /
1
--
Saproling
Token Creature - Saproling
Green
1 /
1
--
Treasure
Token Artifact - Treasure
Colorless
{T}, Sacrifice this artifact: Add one mana of any color.
--
Treasure
Token Artifact - Treasure
Colorless
{T}, Sacrifice this artifact: Add one mana of any color.