Grist, the Hunger Tide

As long as Grist, the Hunger Tide isn't on the battlefield, it's a 1/1 Insect creature in addition to its other types.
+1: Create a 1/1 black and green Insect creature token, then mill a card. If an Insect card was milled this way, put a loyalty counter on Grist and repeat this process.
−2: You may sacrifice a creature. When you do, destroy target creature or planeswalker.
−5: Each opponent loses life equal to the number of creature cards in your graveyard.

Mask of Griselbrand

Equipped creature has flying and lifelink.
Whenever equipped creature dies, you may pay X life, where X is its power. If you do, draw X cards.
Equip {3}

Elder Brain

Menace
Whenever Elder Brain attacks a player, exile all cards from that player's hand, then they draw that many cards. You may play lands and cast spells from among the exiled cards for as long as they remain exiled. If you cast a spell this way, you may spend mana as though it were mana of any color to cast it.

High Market

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

Woodland Cemetery

Woodland Cemetery enters the battlefield tapped unless you control a Swamp or a Forest.
{T}: Add {B} or {G}.

Barter in Blood

Spore Frog

Sacrifice Spore Frog: Prevent all combat damage that would be dealt this turn.

Sol Ring

Sadistic Glee

Enchant creature
Whenever a creature dies, put a +1/+1 counter on enchanted creature.

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.
−9: Each opponent chooses a permanent they control of each permanent type and sacrifices the rest.

Reign of the Pit

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.

Toshiro Umezawa

Bushido 1 (Whenever this creature blocks or becomes blocked, it gets +1/+1 until end of turn.)
Whenever a creature an opponent controls dies, you may cast target instant card from your graveyard. If that spell would be put into a graveyard, exile it instead.

Chain Devil

Animate Chains — When Chain Devil enters the battlefield, each player sacrifices a nontoken creature.

Zombify

Return target creature card from your graveyard to the battlefield.

Rushed Rebirth

Choose target creature. When that creature dies this turn, search your library for a creature card with lesser mana value, put it onto the battlefield tapped, then shuffle.

Innocent Blood

Forest

Blightbelly Rat

Toxic 1 (Players dealt combat damage by this creature also get a poison counter.)
When Blightbelly Rat dies, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Decanter of Endless Water

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

Temple of Malady

Temple of Malady enters the battlefield tapped.
When Temple of Malady enters the battlefield, scry 1.
{T}: Add {B} or {G}.

Black Market

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.

Command Tower

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

Avatar of Woe

If there are ten or more creature cards total in all graveyards, this spell costs {6} less to cast.
Fear (This creature can't be blocked except by artifact creatures and/or black creatures.)
{T}: Destroy target creature. It can't be regenerated.

Grave Pact

Whenever a creature you control dies, each other player sacrifices a creature.

Grisly Salvage

Reveal the top five cards of your library. You may put a creature or land card from among them into your hand. Put the rest into your graveyard.

Chevill, Bane of Monsters

Deathtouch
At the beginning of your upkeep, if your opponents control no permanents with bounty counters on them, put a bounty counter on target creature or planeswalker an opponent controls.
Whenever a permanent an opponent controls with a bounty counter on it dies, you gain 3 life and draw a card.

Rune-Scarred Demon

Flying
When Rune-Scarred Demon enters the battlefield, search your library for a card, put it into your hand, then shuffle.

Gray Merchant of Asphodel

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.)

Archon of Cruelty

Flying
Whenever Archon of Cruelty enters the battlefield or attacks, target opponent sacrifices a creature or planeswalker, discards a card, and loses 3 life. You draw a card and gain 3 life.

Diabolic Tutor

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

Possessed Portal

If a player would draw a card, that player skips that draw instead.
At the beginning of each end step, each player sacrifices a permanent unless they discard a card.

Witherbloom Command

Choose two —
• Target player mills three cards, then you return a land card from your graveyard to your hand.
• Destroy target noncreature, nonland permanent with mana value 2 or less.
• Target creature gets -3/-1 until end of turn.
• Target opponent loses 2 life and you gain 2 life.

Annihilating Glare

As an additional cost to cast this spell, pay {4} or sacrifice an artifact or creature.
Destroy target creature or planeswalker.

Keen Sense

Enchant creature
Whenever enchanted creature deals damage to an opponent, you may draw a card.

Abyssal Gatekeeper

When Abyssal Gatekeeper dies, each player sacrifices a creature.

Whisperwood Elemental

At the beginning of your end step, manifest the top card of your library. (Put it onto the battlefield face down as a 2/2 creature. Turn it face up any time for its mana cost if it's a creature card.)
Sacrifice Whisperwood Elemental: Until end of turn, face-up nontoken creatures you control gain "When this creature dies, manifest the top card of your library."

Momentous Fall

As an additional cost to cast this spell, sacrifice a creature.
You draw cards equal to the sacrificed creature's power, then you gain life equal to its toughness.

Moldervine Reclamation

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

Taste of Death

Each player sacrifices three creatures. You create three Food tokens. (They're artifacts with "{2}, {T}, Sacrifice this artifact: You gain 3 life.")

Sméagol, Helpful Guide

At the beginning of your end step, if a creature died under your control this turn, the Ring tempts you.
Whenever the Ring tempts you, target opponent reveals cards from the top of their library until they reveal a land card. Put that card onto the battlefield tapped under your control and the rest into their graveyard.

Craterhoof Behemoth

Haste
When Craterhoof Behemoth enters the battlefield, creatures you control gain trample and get +X/+X until end of turn, where X is the number of creatures you control.

Deathgreeter

Whenever another creature dies, you may gain 1 life.

Glissa, the Traitor

First strike, deathtouch
Whenever a creature an opponent controls dies, you may return target artifact card from your graveyard to your hand.

Grave Titan

Deathtouch
Whenever Grave Titan enters the battlefield or attacks, create two 2/2 black Zombie creature tokens.

Doomsday Confluence

Choose X. You may choose the same mode more than once.
• Each player sacrifices a nonartifact creature.
• Create a 3/3 black Dalek artifact creature token with menace.
• Each opponent discards a card.

Mortal Combat

At the beginning of your upkeep, if twenty or more creature cards are in your graveyard, you win the game.

Eternal Witness

When Eternal Witness enters the battlefield, you may return target card from your graveyard to your hand.

Lifeline

Whenever a creature dies, if another creature is on the battlefield, return the first card to the battlefield under its owner's control at the beginning of the next end step.

Reliquary Tower

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

Betrayal of Flesh

Choose one —
• Destroy target creature.
• Return target creature card from your graveyard to the battlefield.
Entwine—Sacrifice three lands. (Choose both if you pay the entwine cost.)

Massacre Girl

Menace
When Massacre Girl enters the battlefield, 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.

Ravenous Chupacabra

When Ravenous Chupacabra enters the battlefield, destroy target creature an opponent controls.

Dross Scorpion

Whenever Dross Scorpion or another artifact creature dies, you may untap target artifact.

Guardian Project

Whenever a nontoken creature enters the battlefield under your control, if it doesn't have the same name as another creature you control or a creature card in your graveyard, draw a card.

Necrotic Ooze

As long as Necrotic Ooze is on the battlefield, it has all activated abilities of all creature cards in all graveyards.

Meren of Clan Nel Toth

Whenever another creature you control dies, you get an experience counter.
At the beginning of your end step, choose target creature card in your graveyard. If that card's mana value is less than or equal to the number of experience counters you have, return it to the battlefield. Otherwise, put it into your hand.

Saw in Half

Destroy target creature. If that creature dies this way, its controller creates two tokens that are copies of that creature, except their base power is half that creature's power and their base toughness is half that creature's toughness. Round up each time.

Swamp

Rankle's Prank

Choose one or more —
• Each player discards two cards.
• Each player loses 4 life.
• Each player sacrifices two creatures.

Library of Leng

You have no maximum hand size.
If an effect causes you to discard a card, discard it, but you may put it on top of your library instead of into your graveyard.

Banewhip Punisher

When Banewhip Punisher enters the battlefield, you may put a -1/-1 counter on target creature.
{B}, Sacrifice Banewhip Punisher: Destroy target creature that has a -1/-1 counter on it.

Grim Backwoods

{T}: Add {C}.
{2}{B}{G}, {T}, Sacrifice a creature: Draw a card.

Kaya's Ghostform

Enchant creature or planeswalker you control
When enchanted permanent dies or is put into exile, return that card to the battlefield under your control.

Rise of the Witch-king

Each player sacrifices a creature. If you sacrificed a creature this way, you may return another permanent card from your graveyard to the battlefield.

Josu Vess, Lich Knight

Kicker {5}{B} (You may pay an additional {5}{B} as you cast this spell.)
Menace
When Josu Vess, Lich Knight enters the battlefield, if it was kicked, create eight 2/2 black Zombie Knight creature tokens with menace.

Cankerbloom

{1}, Sacrifice Cankerbloom: Choose one —
• Destroy target artifact.
• Destroy target enchantment.
• Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Necrotic Hex

Each player sacrifices six creatures. You create six tapped 2/2 black Zombie creature tokens.

Abyssal Gorestalker

When Abyssal Gorestalker enters the battlefield, each player sacrifices two creatures.

Whispersteel Dagger

Equipped creature gets +2/+0.
Whenever equipped creature deals combat damage to a player, you may cast a creature spell from that player's graveyard this turn, and you may spend mana as though it were mana of any color to cast that spell.
Equip {3}

Adaptive Sporesinger

Vigilance
When Adaptive Sporesinger enters the battlefield, choose one —
• Target creature gets +2/+2 and gains vigilance until end of turn.
• Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Vat of Rebirth

Whenever another artifact or creature you control is put into a graveyard from the battlefield, put an oil counter on Vat of Rebirth.
{2}{B}, {T}, Remove four oil counters from Vat of Rebirth: Return target creature card from your graveyard to the battlefield. Activate only as a sorcery.