Nightmare

Flying (This creature can't be blocked except by creatures with flying or reach.)
Nightmare's power and toughness are each equal to the number of Swamps you control.

Haunted Fengraf

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

Languish

All creatures get -4/-4 until end of turn.

Plaguecrafter

When Plaguecrafter enters, each player sacrifices a creature or planeswalker. Each player who can't discards a card.

Demon's Disciple

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

Zulaport Cutthroat

Whenever Zulaport Cutthroat or another 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.)

Death-Rattle Oni

Flash
This spell costs {2} less to cast for each creature that died this turn.
When Death-Rattle Oni enters, destroy all other creatures that were dealt damage this turn.

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.)

Gray Merchant of Asphodel

When Gray Merchant of Asphodel enters, 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.)

Dross Skullbomb

{1}, Sacrifice Dross Skullbomb: Draw a card.
{2}{B}, Sacrifice Dross Skullbomb: Return target creature card from your graveyard to your hand. Draw a card. Activate only as a sorcery.

Burnished Hart

{3}, Sacrifice Burnished Hart: Search your library for up to two basic land cards, put them onto the battlefield tapped, then shuffle.

Angel of Suffering

Flying
If damage would be dealt to you, prevent that damage and mill twice that many cards.

Dark Ritual

Mindwrack Harpy

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

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.

Death Denied

Return X target creature cards from your graveyard to your hand.

Sign in Blood

Target player draws two cards and loses 2 life.

Reassembling Skeleton

{1}{B}: Return Reassembling Skeleton from your graveyard to the battlefield tapped.

Phyrexian Arena

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

Sanitarium Skeleton

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

Mortuary Mire

Mortuary Mire enters tapped.
When Mortuary Mire enters, you may put target creature card from your graveyard on top of your library.
{T}: Add {B}.

Undertaker

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

Fleshbag Marauder

When Fleshbag Marauder enters, each player sacrifices a creature.

Underworld Dreams

Whenever an opponent draws a card, Underworld Dreams deals 1 damage to that player.

Hypnotic Specter

Flying
Whenever Hypnotic Specter deals damage to an opponent, that player discards a card at random.

Sivriss, Nightmare Speaker

{T}, Sacrifice another creature or an artifact: For each opponent, you mill a card, then return that card from your graveyard to your hand unless that player pays 3 life. (To mill a card, put the top card of your library into your graveyard.)
Choose a Background (You can have a Background as a second commander.)

Leaden Myr

Ravenous Gigamole

When Ravenous Gigamole enters, 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.)

Breach the Multiverse

Each player mills ten cards. For each player, choose a creature or planeswalker card in that player's graveyard. Put those cards onto the battlefield under your control. Then each creature you control becomes a Phyrexian in addition to its other types.

Blood Artist

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

Vraan, Executioner Thane

Whenever one or more other creatures you control die, each opponent loses 2 life and you gain 2 life. This ability triggers only once each turn.

Innocent Blood

Songs of the Damned

Add {B} for each creature card in 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.")

Shriekmaw

Fear (This creature can't be blocked except by artifact creatures and/or black creatures.)
When Shriekmaw enters, destroy target nonartifact, nonblack creature.
Evoke {1}{B} (You may cast this spell for its evoke cost. If you do, it's sacrificed when it enters.)

Witch's Cottage

({T}: Add {B}.)
Witch's Cottage enters tapped unless you control three or more other Swamps.
When Witch's Cottage enters untapped, you may put target creature card from your graveyard on top of your library.

Omen of the Dead

Flash
When Omen of the Dead enters, return target creature card from your graveyard to your hand.
{2}{B}, Sacrifice Omen of the Dead: Scry 2.

Mindcrank

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

Undercity Informer

{1}, Sacrifice a creature: Target player reveals cards from the top of their library until they reveal a land card, then puts those cards into their graveyard.

Heraldic Banner

As Heraldic Banner enters, choose a color.
Creatures you control of the chosen color get +1/+0.
{T}: Add one mana of the chosen color.

Macabre Waltz

Return up to two target creature cards from your graveyard to your hand, then discard a card.

Memorial to Folly

Memorial to Folly enters tapped.
{T}: Add {B}.
{2}{B}, {T}, Sacrifice Memorial to Folly: Return target creature card from your graveyard to your hand.

Murder

Corpse Augur

When Corpse Augur dies, you draw X cards and you lose X life, where X is the number of creature cards in target player's graveyard.

Bojuka Bog

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

Eye Collector

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

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.

Carrion Feeder

Carrion Feeder can't block.
Sacrifice a creature: Put a +1/+1 counter on Carrion Feeder.

Buried Ruin

{T}: Add {C}.
{2}, {T}, Sacrifice Buried Ruin: Return target artifact card from your graveyard to your hand.

Vile Entomber

Deathtouch
When Vile Entomber enters, search your library for a card, put that card into your graveyard, then shuffle.

Hell's Caretaker

{T}, Sacrifice a creature: Return target creature card from your graveyard to the battlefield. Activate only during your upkeep.

Cult Conscript

Cult Conscript enters tapped.
{1}{B}: Return Cult Conscript from your graveyard to the battlefield. Activate only if a non-Skeleton creature died under your control this turn.

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.)

Nihil Spellbomb

{T}, Sacrifice Nihil Spellbomb: Exile target player's graveyard.
When Nihil Spellbomb is put into a graveyard from the battlefield, you may pay {B}. If you do, draw a card.

Waste Not

Whenever an opponent discards a creature card, create a 2/2 black Zombie creature token.
Whenever an opponent discards a land card, add {B}{B}.
Whenever an opponent discards a noncreature, nonland card, draw a card.

Final Parting

Search your library for two cards. Put one into your hand and the other into your graveyard. Then shuffle.

Grisly Spectacle

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

Mesmeric Orb

Whenever a permanent becomes untapped, that permanent's controller mills a card.

Balustrade Spy

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

In Garruk's Wake

Destroy all creatures you don't control and all planeswalkers you don't control.

Ghoulish Procession

Whenever one or more nontoken creatures die, create a 2/2 black Zombie creature token with decayed. This ability triggers only once each turn. (A creature with decayed can't block. When it attacks, sacrifice it at end of combat.)

Summon Undead

You may mill three cards. Then return a creature card from your graveyard to the battlefield. (To mill a card, put the top card of your library into your graveyard.)

Codex Shredder

{T}: Target player mills a card. (They put the top card of their library into their graveyard.)
{5}, {T}, Sacrifice Codex Shredder: Return target card from your graveyard to your hand.

Phyrexian Reclamation

{1}{B}, Pay 2 life: Return target creature card from your graveyard to your hand.

Forever Young

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

Fell Stinger

Deathtouch
Exploit (When this creature enters, you may sacrifice a creature.)
When Fell Stinger exploits a creature, target player draws two cards and loses 2 life.

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.)

Golgari Thug

When Golgari Thug dies, put target creature card from your graveyard on top of your library.
Dredge 4 (If you would draw a card, you may mill four cards instead. If you do, return this card from your graveyard to your hand.)

Bad Moon

Skulking Ghost

Flying
When Skulking Ghost becomes the target of a spell or ability, sacrifice it.

Footbottom Feast

Gravelighter

Flying
When Gravelighter enters, draw a card if a creature died this turn. Otherwise, each player sacrifices a creature.

Ravenous Chupacabra

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

Dark Deal

Each player discards all the cards in their hand, then draws that many cards minus one.

Swamp

Falkenrath Noble

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

Braids's Frightful Return

Read ahead (Choose a chapter and start with that many lore counters. Add one after your draw step. Skipped chapters don't trigger. Sacrifice after III.)
I — You may sacrifice a creature. If you do, each opponent discards a card.
II — Return target creature card from your graveyard to your hand.
III — Target opponent may sacrifice a nonland, nontoken permanent. If they don't, they lose 2 life and you draw a card.