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.

Decree of Pain

Destroy all creatures. They can't be regenerated. Draw a card for each creature destroyed this way.
Cycling {3}{B}{B} ({3}{B}{B}, Discard this card: Draw a card.)
When you cycle Decree of Pain, all creatures get -2/-2 until end of turn.

Sol Ring

Wasteland

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

Toxic Deluge

As an additional cost to cast this spell, pay X life.
All creatures get -X/-X until end of turn.

Forbidden Orchard

{T}: Add one mana of any color.
Whenever you tap Forbidden Orchard for mana, target opponent creates a 1/1 colorless Spirit creature token.

Phyrexian Tower

{T}: Add {C}.
{T}, Sacrifice a creature: Add {B}{B}.

Thespian's Stage

{T}: Add {C}.
{2}, {T}: Thespian's Stage becomes a copy of target land, except it has this ability.

The Meathook Massacre

When The Meathook Massacre enters, each creature gets -X/-X until end of turn.
Whenever a creature you control dies, each opponent loses 1 life.
Whenever a creature an opponent controls dies, you gain 1 life.

Falkenrath Noble

Flying
Whenever Falkenrath Noble or another creature dies, target player loses 1 life and you gain 1 life.

Sangromancer

Flying
Whenever a creature an opponent controls dies, you may gain 3 life.
Whenever an opponent discards a card, you may gain 3 life.

Liliana, Defiant Necromancer

+2: Each player discards a card.
−X: Return target nonlegendary creature card with mana value X from your graveyard to the battlefield.
−8: You get an emblem with "Whenever a creature dies, return it to the battlefield under your control at the beginning of the next end step."

Liliana, Heretical Healer

Lifelink
Whenever another nontoken creature you control dies, exile Liliana, Heretical Healer, then return her to the battlefield transformed under her owner's control. If you do, create a 2/2 black Zombie creature token.

Liliana, Heretical Healer // Liliana, Defiant Necromancer

Wayfarer's Bauble

{2}, {T}, Sacrifice Wayfarer's Bauble: Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Sanctum of Eternity

{T}: Add {C}.
{2}, {T}: Return target commander you own from the battlefield to your hand. Activate only during your turn.

High Market

{T}: Add {C}.
{T}, Sacrifice a creature: You gain 1 life.

Black Market Connections

At the beginning of your first main phase, choose one or more —
• Sell Contraband — Create a Treasure token. You lose 1 life.
• Buy Information — Draw a card. You lose 2 life.
• Hire a Mercenary — Create a 3/2 colorless Shapeshifter creature token with changeling. You lose 3 life. (It has every creature type.)

Cabal Coffers

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

Thrilling Encore

Put onto the battlefield under your control all creature cards in all graveyards that were put there from the battlefield this turn.

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.)

Sengir, the Dark Baron

Flying
Whenever another creature dies, put two +1/+1 counters on Sengir, the Dark Baron.
Whenever another player loses the game, you gain life equal to that player's life total as the turn began.
Partner (You can have two commanders if both have partner.)

Bontu's Monument

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.

Bone Harvest

Put any number of target creature cards from your graveyard on top of your library.
Draw a card at the beginning of the next turn's upkeep.

Crowded Crypt

{T}: Add {B}.
Whenever a creature you control dies, put a corpse counter on Crowded Crypt.
{4}{B}{B}, {T}, Sacrifice Crowded Crypt: Create a 2/2 black Zombie creature token with decayed for each corpse counter on Crowded Crypt. (A creature with decayed can't block. When it attacks, sacrifice it at end of combat.)

Echo of Death's Wail

Flying, haste
When Echo of Death's Wail enters, gain control of all Rat tokens.
Whenever Echo of Death's Wail attacks, you may sacrifice another creature. If you do, draw a card.

Tribute to Horobi

(As this Saga enters and after your draw step, add a lore counter.)
I, II — Each opponent creates a 1/1 black Rat Rogue creature token.
III — Exile this Saga, then return it to the battlefield transformed under your control.

Tribute to Horobi // Echo of Death's Wail

Scavenger Drake

Flying
Whenever another creature dies, you may put a +1/+1 counter on Scavenger Drake.

Erratic Portal

{1}, {T}: Return target creature to its owner's hand unless its controller pays {1}.

Venomcrawler

Lifelink
Devourer of Souls — Whenever another creature dies, put a +1/+1 counter on Venomcrawler.

Rise of the Dark Realms

Put all creature cards from all graveyards onto the battlefield under your control.

Corrupted Conviction

As an additional cost to cast this spell, sacrifice a creature.
Draw two cards.

Bloodchief Ascension

At the beginning of each end step, if an opponent lost 2 or more life this turn, you may put a quest counter on Bloodchief Ascension. (Damage causes loss of life.)
Whenever a card is put into an opponent's graveyard from anywhere, if Bloodchief Ascension has three or more quest counters on it, you may have that player lose 2 life. If you do, you gain 2 life.

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.

Plumb the Forbidden

As an additional cost to cast this spell, you may sacrifice one or more creatures. When you do, copy this spell for each creature sacrificed this way.
You draw a card and you lose 1 life.

Pitiless Plunderer

Whenever another creature you control dies, create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Necropotence

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.

Infernal Grasp

Destroy target creature. You lose 2 life.

Expedition Map

{2}, {T}, Sacrifice this artifact: Search your library for a land card, reveal it, put it into your hand, then shuffle.

Phyrexian Arena

At the beginning of your upkeep, you draw a card and you lose 1 life.

Skullclamp

Equipped creature gets +1/-1.
Whenever equipped creature dies, draw two cards.
Equip {1}

Dread Presence

Whenever a Swamp you control enters, choose one —
• You draw a card and you lose 1 life.
• Dread Presence deals 2 damage to any target and you gain 2 life.

Mind Stone

{T}: Add {C}.
{1}, {T}, Sacrifice Mind Stone: Draw a card.

Bastion of Remembrance

When Bastion of Remembrance enters, create a 1/1 white Human Soldier creature token.
Whenever a creature you control dies, each opponent loses 1 life and you gain 1 life.

Syr Konrad, the Grim

Whenever another creature dies, or a creature card is put into a graveyard from anywhere other than the battlefield, or a creature card leaves your graveyard, Syr Konrad, the Grim deals 1 damage to each opponent.
{1}{B}: Each player mills a card. (They each put the top card of their library into their graveyard.)

Erebos, Bleak-Hearted

Indestructible
As long as your devotion to black is less than five, Erebos isn't a creature.
Whenever another creature you control dies, you may pay 2 life. If you do, draw a card.
{1}{B}, Sacrifice another creature: Target creature gets -2/-1 until end of turn.

Cavalier of Night

Lifelink
When Cavalier of Night enters, you may sacrifice another creature. When you do, destroy target creature an opponent controls.
When Cavalier of Night dies, return target creature card with mana value 3 or less from your graveyard to the battlefield.

Bloodcrazed Paladin

Flash
Bloodcrazed Paladin enters with a +1/+1 counter on it for each creature that died this turn.

Jet Medallion

Black spells you cast cost {1} less to cast.

Vampiric Tutor

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

Tarrian's Soulcleaver

Equipped creature has vigilance.
Whenever another artifact or creature is put into a graveyard from the battlefield, put a +1/+1 counter on equipped creature.
Equip {2}

Reassembling Skeleton

{1}{B}: Return this card from your graveyard to the battlefield tapped.

Volrath's Stronghold

{T}: Add {C}.
{1}{B}, {T}: Put target creature card from your graveyard on top of your library.

Decanter of Endless Water

You have no maximum hand size.
{T}: Add one mana of any color.

Ogre Slumlord

Whenever another nontoken creature dies, you may create a 1/1 black Rat creature token.
Rats you control have deathtouch.

Swamp

Grim Tutor

Search your library for a card, put that card into your hand, then shuffle. You lose 3 life.

Blood Artist

Whenever Blood Artist or another creature dies, target player loses 1 life and you gain 1 life.

Liliana, Dreadhorde General

Whenever a creature you control dies, draw a card.
+1: Create a 2/2 black Zombie creature token.
−4: Each player sacrifices two creatures of their choice.
−9: Each opponent chooses a permanent they control of each permanent type and sacrifices the rest.

Thought Vessel

You have no maximum hand size.
{T}: Add {C}.

Arcane Signet

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

Phyrexian Etchings

Cumulative upkeep {B} (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)
At the beginning of your end step, draw a card for each age counter on Phyrexian Etchings.
When Phyrexian Etchings is put into a graveyard from the battlefield, you lose 2 life for each age counter on it.

Bitterblossom

At the beginning of your upkeep, you lose 1 life and create a 1/1 black Faerie Rogue creature token with flying.

Reliquary Tower

Feed the Swarm

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

Urborg, Tomb of Yawgmoth

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

Necrosynthesis

Enchant creature
Enchanted creature has "Whenever another creature dies, put a +1/+1 counter on this creature."
When enchanted creature dies, look at the top X cards of your library, where X is its power. Put one of those cards into your hand and the rest on the bottom of your library in a random order.

Dark Prophecy

Whenever a creature you control dies, you draw a card and you lose 1 life.

Throne of Eldraine

As Throne of Eldraine enters, choose a color.
{T}: Add four mana of the chosen color. Spend this mana only to cast monocolored spells of that color.
{3}, {T}: Draw two cards. Spend only mana of the chosen color to activate this ability.

Tevesh Szat, Doom of Fools

+2: Create two 0/1 black Thrull creature tokens.
+1: You may sacrifice another creature or planeswalker. If you do, draw two cards, then draw another card if the sacrificed permanent was a commander.
−10: Gain control of all commanders. Put all commanders from the command zone onto the battlefield under your control.
Tevesh Szat, Doom of Fools can be your commander.
Partner

God-Eternal Bontu

Menace
When God-Eternal Bontu enters, sacrifice any number of other permanents, then draw that many cards.
When God-Eternal Bontu dies or is put into exile from the battlefield, you may put it into its owner's library third from the top.

Deadly Rollick

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

Snuff Out

If you control a Swamp, you may pay 4 life rather than pay this spell's mana cost.
Destroy target nonblack creature. It can't be regenerated.

Body Count

Spectacle {B} (You may cast this spell for its spectacle cost rather than its mana cost if an opponent lost life this turn.)
Draw a card for each creature that died under your control this turn.

Liliana's Standard Bearer

Flash
When Liliana's Standard Bearer enters, draw X cards, where X is the number of creatures that died under your control this turn.

Bojuka Bog

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

Grim Haruspex

Morph {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.)
Whenever another nontoken creature you control dies, draw a card.

Zulaport Cutthroat

Whenever Zulaport Cutthroat or another creature you control dies, each opponent loses 1 life and you gain 1 life.

Sudden Spoiling

Split second (As long as this spell is on the stack, players can't cast spells or activate abilities that aren't mana abilities.)
Until end of turn, creatures target player controls lose all abilities and have base power and toughness 0/2.

Vogar, Necropolis Tyrant

Menace
Whenever another creature dies during your turn, put a +1/+1 counter on Vogar, Necropolis Tyrant.
When Vogar dies, draw a card for each +1/+1 counter on it.

Mindcrank

Whenever an opponent loses life, that player mills that many cards. (Damage causes loss of life.)

Blade of the Bloodchief

Whenever a creature dies, put a +1/+1 counter on equipped creature. If equipped creature is a Vampire, put two +1/+1 counters on it instead.
Equip {1}

Baleful Mastery

You may pay {1}{B} rather than pay this spell's mana cost.
If the {1}{B} cost was paid, an opponent draws a card.
Exile target creature or planeswalker.

Miren, the Moaning Well

{T}: Add {C}.
{3}, {T}, Sacrifice a creature: You gain life equal to the sacrificed creature's toughness.

Black Market

Whenever a creature dies, put a charge counter on Black Market.
At the beginning of your first main phase, add {B} for each charge counter on Black Market.

Crypt Ghast

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}.

Massacre Girl

Menace
When Massacre Girl enters, each other creature gets -1/-1 until end of turn. Whenever a creature dies this turn, each creature other than Massacre Girl gets -1/-1 until end of turn.

Dark Ritual

Erebos's Intervention

Choose one —
• Target creature gets -X/-X until end of turn. You gain X life.
• Exile up to twice X target cards from graveyards.

Spoils of Blood

Create an X/X black Horror creature token, where X is the number of creatures that died this turn.