Have

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.)

Getting

Sanitarium Skeleton

{2}{B}: Return Sanitarium Skeleton from your graveyard to your hand.

Discerning Taste

Look at the top four cards of your library. Put one of them into your hand and the rest into your graveyard. You gain life equal to the greatest power among creature cards put into your graveyard this way.

Stinkweed Imp

Flying
Whenever Stinkweed Imp deals combat damage to a creature, destroy that creature.
Dredge 5 (If you would draw a card, you may mill five cards instead. If you do, return this card from your graveyard to your hand.)

Undertaker

{B}, {T}, Discard a card: Return target creature card from your graveyard to your hand.

Venomous Hierophant

Deathtouch
When Venomous Hierophant enters the battlefield, mill three cards. (Put the top three cards of your library into your graveyard.)

Deadly Dispute

As an additional cost to cast this spell, sacrifice an artifact or creature.
Draw two cards and create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Tragic Slip

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.

Sibsig Host

When Sibsig Host enters the battlefield, each player mills three cards.

Tocasia's Dig Site

{T}: Add {C}.
{3}, {T}: Surveil 1. (Look at the top card of your library. You may put it into your graveyard.)

Don't Have

First-Sphere Gargantua

When First-Sphere Gargantua enters the battlefield, you draw a card and you lose 1 life.
Unearth {2}{B} ({2}{B}: Return this card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the next end step or if it would leave the battlefield. Unearth only as a sorcery.)

Haunted Fengraf

{T}: Add {C}.
{3}, {T}, Sacrifice Haunted Fengraf: Return a creature card at random from your graveyard to your hand.

Crow of Dark Tidings

Flying
When Crow of Dark Tidings enters the battlefield or dies, mill two cards. (Put the top two cards of your library into your graveyard.)

Another Chance

You may mill two cards. Then return up to two creature cards from your graveyard to your hand. (To mill two cards, put the top two cards of your library into your graveyard.)

Dark Ritual

Unseal the Necropolis

Each player mills three cards. Then you return up to two creature cards from your graveyard to your hand. (To mill three cards, a player puts the top three cards of their library into their graveyard.)

Entropic Decay

Mill four cards. (Then exile this card. You may cast the creature later from exile.)

Gray Slaad

As long as there are four or more creature cards in your graveyard, Gray Slaad has menace and deathtouch.

Gray Slaad // Entropic Decay

Read the Bones

Scry 2, then draw two cards. You lose 2 life.

Hedron Crawler

{T}: Add {C}. ({C} represents colorless mana.)

Underworld Charger

Underworld Charger can't block.
Escape—{4}{B}, Exile three other cards from your graveyard. (You may cast this card from your graveyard for its escape cost.)
Underworld Charger escapes with two +1/+1 counters on it.

Bog Witch

Songs of the Damned

Add {B} for each creature card in your graveyard.

Soldevi Adnate

{T}, Sacrifice a black or artifact creature: Add an amount of {B} equal to the sacrificed creature's mana value.

Tenured Oilcaster

Menace (This creature can't be blocked except by two or more creatures.)
Tenured Oilcaster gets +3/+0 as long as an opponent has eight or more cards in their graveyard.
Whenever Tenured Oilcaster attacks or blocks, each player mills a card.

Crypt Rats

{X}: Crypt Rats deals X damage to each creature and each player. Spend only black mana on X.

Vicious Rumors

Vicious Rumors deals 1 damage to each opponent. Each opponent discards a card, then mills a card. You gain 1 life.

Gorging Vulture

Flying
When Gorging Vulture enters the battlefield, mill four cards. You gain 1 life for each creature card milled this way. (To mill four cards, put the top four cards of your library into your graveyard.)

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.)

Forever Young

Put any number of target creature cards from your graveyard on top of your library.
Draw a card.

Syphon Mind

Each other player discards a card. You draw a card for each card discarded this way.

Bojuka Bog

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

Ghoulcaller's Bell

Ravenous Gigamole

When Ravenous Gigamole enters the battlefield, mill three cards. You may put a creature card from among the cards milled this way into your hand. If you don't, put a +1/+1 counter on Ravenous Gigamole. (To mill a card, put the top card of your library into your graveyard.)

Screaming Phantom

Flying
Whenever Screaming Phantom attacks, mill a card. (Put the top card of your library into your graveyard.)

Eerie Soultender

When Eerie Soultender enters the battlefield, mill three cards. (To mill a card, put the top card of your library into your graveyard.)
{4}{B}, Exile Eerie Soultender from your graveyard: Return another target creature card from your graveyard to your hand.

Sign in Blood

Target player draws two cards and loses 2 life.

Leaden Myr

Manakin

Witch's Cottage

({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.

Wailing Ghoul

When Wailing Ghoul enters the battlefield, mill two cards.

Demon's Disciple

When Demon's Disciple enters the battlefield, each player sacrifices a creature or planeswalker.

Persistent Specimen

{2}{B}: Return Persistent Specimen from your graveyard to the battlefield tapped.

Crypt Incursion

Exile all creature cards from target player's graveyard. You gain 3 life for each card exiled this way.

Ornithopter of Paradise

Atrocious Experiment

Target player mills two cards, draws two cards, and loses 2 life. (To mill a card, a player puts the top card of their library into their graveyard.)

Mindwrack Harpy

Flying
At the beginning of combat on your turn, each player mills three cards.

Overwhelming Remorse

This spell costs {1} less to cast for each creature card in your graveyard.
Exile target creature or planeswalker.

Dimir House Guard

Fear (This creature can't be blocked except by artifact creatures and/or black creatures.)
Sacrifice a creature: Regenerate Dimir House Guard.
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 shuffle. Transmute only as a sorcery.)

Returned Reveler

When Returned Reveler dies, each player mills three cards.

Defile

Target creature gets -1/-1 until end of turn for each Swamp you control.

Sinister Starfish

{T}: Surveil 1. (Look at the top card of your library. You may put it into your graveyard.)

Returned Centaur

When Returned Centaur enters the battlefield, target player mills four cards.

Feign Death

Until end of turn, target creature gains "When this creature dies, return it to the battlefield tapped under its owner's control with a +1/+1 counter on it."

Grisly Spectacle

Destroy target nonartifact creature. Its controller mills cards equal to that creature's power.

Hidden Necropolis

Hidden Necropolis enters the battlefield tapped.
{T}: Add {B}.
{4}{B}, {T}, Sacrifice Hidden Necropolis: Discover 4. Activate only as a sorcery. (Exile cards from the top of your library until you exile a nonland card with mana value 4 or less. Cast it without paying its mana cost or put it into your hand. Put the rest on the bottom in a random order.)

Tortured Existence

{B}, Discard a creature card: Return target creature card from your graveyard to your hand.

Corpse Churn

Mill three cards, then you may return a creature card from your graveyard to your hand. (To mill three cards, put the top three cards of your library into your graveyard.)

Funeral Rites

You draw two cards, lose 2 life, then mill two cards.

Village Rites

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

Cadaver Imp

Flying
When Cadaver Imp enters the battlefield, you may return target creature card from your graveyard to your hand.

Swamp

Flitting Guerrilla

Flying
When Flitting Guerrilla dies, each player mills two cards. Then you may exile Flitting Guerrilla. When you do, put target creature or battle card from your graveyard on top of your library. (To mill two cards, a player puts the top two cards of their library into their graveyard.)

Footbottom Feast

Eye Collector

Flying
Whenever Eye Collector deals combat damage to a player, each player mills a card.

Feldon's Cane

{T}, Exile Feldon's Cane: Shuffle your graveyard into your library.

Mortuary Mire

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}.

Balustrade Spy

Flying
When Balustrade Spy enters the battlefield, target player reveals cards from the top of their library until they reveal a land card, then puts those cards into their graveyard.

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.

Koma's Faithful

Lifelink
When Koma's Faithful dies, each player mills three cards. (To mill a card, a player puts the top card of their library into their graveyard.)

Fleshbag Marauder

When Fleshbag Marauder enters the battlefield, each player sacrifices a creature.

Wight of Precinct Six

Wight of Precinct Six gets +1/+1 for each creature card in your opponents' graveyards.