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
{1}{B}{B}
Ashes to Ashes
Sorcery
Exile two target nonartifact creatures. Ashes to Ashes deals 5 damage to you.
{3}
Ashnod's Altar
Artifact
Sacrifice a creature: Add {C}{C}.
{3}{B}{B}
Black Market
Enchantment
Whenever a creature dies, put a charge counter on Black Market.
At the beginning of your precombat main phase, add {B} for each charge counter on Black Market.
{3}
Blasting Station
Artifact
{T}, Sacrifice a creature: Blasting Station deals 1 damage to any target.
Whenever a creature enters the battlefield, you may untap Blasting Station.
{1}{B}
Blood Artist
Creature - Vampire
Whenever Blood Artist or another creature dies, target player loses 1 life and you gain 1 life.
0 /
1
{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
{2}{B}
Bloodthirsty Ogre
Creature - Ogre Warrior Shaman
{T}: Put a devotion counter on Bloodthirsty Ogre.
{T}: Target creature gets -X/-X until end of turn, where X is the number of devotion counters on Bloodthirsty Ogre. Activate only if you control a Demon.
3 /
1
--
Bojuka Bog
Land
Bojuka Bog enters the battlefield tapped.
When Bojuka Bog enters the battlefield, exile target player's graveyard.
{T}: Add {B}.
{3}
Burnished Hart
Artifact Creature - Elk
{3}, Sacrifice Burnished Hart: Search your library for up to two basic land cards, put them onto the battlefield tapped, then shuffle.
2 /
2
--
Cabal Coffers
Land
{2}, {T}: Add {B} for each Swamp you control.
{2}
Charcoal Diamond
Artifact
Charcoal Diamond enters the battlefield tapped.
{T}: Add {B}.
{2}
Coldsteel Heart
Snow Artifact
Coldsteel Heart enters the battlefield tapped.
As Coldsteel Heart enters the battlefield, choose a color.
{T}: Add one mana of the chosen color.
{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
{B}
Deathgreeter
Creature - Human Shaman
Whenever another creature dies, you may gain 1 life.
1 /
1
{3}{B}{B}{B}
Demon of Dark Schemes
Creature - Demon
Flying
When Demon of Dark Schemes enters the battlefield, all other creatures get -2/-2 until end of turn.
Whenever another creature dies, you get {E} (an energy counter).
{2}{B}, Pay {E}{E}{E}{E}: Put target creature card from a graveyard onto the battlefield under your control tapped.
5 /
5
{2}{B}
Demonic Taskmaster
Creature - Demon
Flying
At the beginning of your upkeep, sacrifice a creature other than Demonic Taskmaster.
4 /
3
{2}{B}{B}
Demonlord of Ashmouth
Creature - Demon
Flying
When Demonlord of Ashmouth enters the battlefield, exile it unless you sacrifice another creature.
Undying (When this creature dies, if it had no +1/+1 counters on it, return it to the battlefield under its owner's control with a +1/+1 counter on it.)
5 /
4
{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
{5}{B}{B}
Eater of Hope
Creature - Demon
Flying
{B}, Sacrifice another creature: Regenerate Eater of Hope.
{2}{B}, Sacrifice two other creatures: Destroy target creature.
6 /
4
{4}{B}
Endrek Sahr, Master Breeder
Legendary Creature - Human Wizard
Whenever you cast a creature spell, create X 1/1 black Thrull creature tokens, where X is that spell's mana value.
When you control seven or more Thrulls, sacrifice Endrek Sahr, Master Breeder.
2 /
2
{4}{B}
Exquisite Blood
Enchantment
Whenever an opponent loses life, you gain that much life.
{B}{B}
Gate to Phyrexia
Enchantment
Sacrifice a creature: Destroy target artifact. Activate only during your upkeep and only once each turn.
{3}{B}{B}
Gray Merchant of Asphodel
Creature - Zombie
When Gray Merchant of Asphodel enters the battlefield, 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.)
2 /
4
{2}{B}{B}
Grinning Demon
Creature - Demon
At the beginning of your upkeep, you lose 2 life.
Morph {2}{B}{B} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)
6 /
6
{1}{B}
Heartless Summoning
Enchantment
Creature spells you cast cost {2} less to cast.
Creatures you control get -1/-1.
{1}{B}{B}
Hecatomb
Enchantment
When Hecatomb enters the battlefield, sacrifice Hecatomb unless you sacrifice four creatures.
Tap an untapped Swamp you control: Hecatomb deals 1 damage to any target.
{3}{B}
Hell's Caretaker
Creature - Horror
{T}, Sacrifice a creature: Return target creature card from your graveyard to the battlefield. Activate only during your upkeep.
1 /
1
--
High Market
Land
{T}: Add {C}.
{T}, Sacrifice a creature: You gain 1 life.
{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.)
{2}{B}{B}
Liliana of the Dark Realms
Legendary Planeswalker - Liliana
+1: Search your library for a Swamp card, reveal it, put it into your hand, then shuffle.
-3: Target creature gets +X/+X or -X/-X until end of turn, where X is the number of Swamps you control.
-6: You get an emblem with "Swamps you control have '{T}: Add {B}{B}{B}{B}.'"
L:
3
{4}{B}
Magus of the Coffers
Creature - Human Wizard
{2}, {T}: Add {B} for each Swamp you control.
4 /
4
{2}
Mind Stone
Artifact
{T}: Add {C}.
{1}, {T}, Sacrifice Mind Stone: Draw a card.
{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
--
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.
{B}{B}{B}
Necropotence
Enchantment
Skip your draw step.
Whenever you discard a card, exile that card from your graveyard.
Pay 1 life: Exile the top card of your library face down. Put that card into your hand at the beginning of your next end step.
--
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.)
{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}
Phyrexian Altar
Artifact
Sacrifice a creature: Add one mana of any color.
{1}{B}{B}
Phyrexian Arena
Enchantment
At the beginning of your upkeep, you draw a card and you lose 1 life.
{B}{B}{B}{B}
Phyrexian Obliterator
Creature - Phyrexian Horror
Trample
Whenever a source deals damage to Phyrexian Obliterator, that source's controller sacrifices that many permanents.
5 /
5
{3}{B}{B}
Phyrexian Plaguelord
Creature - Phyrexian Carrier
{T}, Sacrifice Phyrexian Plaguelord: Target creature gets -4/-4 until end of turn.
Sacrifice a creature: Target creature gets -1/-1 until end of turn.
4 /
4
{3}
Phyrexian Totem
Artifact
{T}: Add {B}.
{2}{B}: Phyrexian Totem becomes a 5/5 black Phyrexian Horror artifact creature with trample until end of turn.
Whenever Phyrexian Totem is dealt damage, if it's a creature, sacrifice that many permanents.
{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
{2}{B}{B}
Reprocess
Sorcery
Sacrifice any number of artifacts, creatures, and/or lands. Draw a card for each permanent sacrificed this way.
{3}{B}{B}
Shadowborn Demon
Creature - Demon
Flying
When Shadowborn Demon enters the battlefield, destroy target non-Demon creature.
At the beginning of your upkeep, if there are fewer than six creature cards in your graveyard, sacrifice a creature.
5 /
6
{3}{B}{B}
Sidisi, Undead Vizier
Legendary Creature - Zombie Naga
Deathtouch
Exploit (When this creature enters the battlefield, you may sacrifice a creature.)
When Sidisi, Undead Vizier exploits a creature, you may search your library for a card, put it into your hand, then shuffle.
4 /
6
{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
{1}
Skullclamp
Artifact - Equipment
Equipped creature gets +1/-1.
Whenever equipped creature dies, draw two cards.
Equip {1}
{2}{B}{B}
Smothering Abomination
Creature - Eldrazi
Devoid (This card has no color.)
Flying
At the beginning of your upkeep, sacrifice a creature.
Whenever you sacrifice a creature, draw a card.
4 /
3
{1}
Sol Ring
Artifact
{T}: Add {C}{C}.
{2}
Spawning Pit
Artifact
Sacrifice a creature: Put a charge counter on Spawning Pit.
{1}, Remove two charge counters from Spawning Pit: Create a 2/2 colorless Spawn artifact creature token.
--
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}.)
--
Swamp
Basic Land - Swamp
({T}: Add {B}.)
--
Temple of the False God
Land
{T}: Add {C}{C}. Activate only if you control five or more lands.
{B}
Thoughtpicker Witch
Creature - Human Wizard
{1}, Sacrifice a creature: Look at the top two cards of target opponent's library, then exile one of them.
1 /
1
{B}
Tragic Slip
Instant
Target creature gets -1/-1 until end of turn.
Morbid -- That creature gets -13/-13 until end of turn instead if a creature died this turn.
{1}{B}, Sacrifice a creature: You gain 1 life and draw a card.
{B}
Viscera Seer
Creature - Vampire Wizard
Sacrifice a creature: Scry 1. (Look at the top card of your library. You may put that card on the bottom of your library.)
1 /
1
--
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
{2}{B}{B}
Whip of Erebos
Legendary Enchantment Artifact
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.
{3}
Worn Powerstone
Artifact
Worn Powerstone enters the battlefield tapped.
{T}: Add {C}{C}.
{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
{1}{B}
Zulaport Cutthroat
Creature - Human Rogue Ally
Whenever Zulaport Cutthroat or another creature you control dies, each opponent loses 1 life and you gain 1 life.