Quest for the Nihil Stone

Whenever an opponent discards a card, you may put a quest counter on Quest for the Nihil Stone.
At the beginning of each opponent's upkeep, if that player has no cards in hand and Quest for the Nihil Stone has two or more quest counters on it, you may have that player lose 5 life.

Cabal Stronghold

{T}: Add {C}.
{3}, {T}: Add {B} for each basic Swamp you control.

Painful Quandary

Whenever an opponent casts a spell, that player loses 5 life unless they discard a card.

Geier Reach Sanitarium

{T}: Add {C}.
{2}, {T}: Each player draws a card, then discards a card.

Liliana, Waker of the Dead

+1: Each player discards a card. Each opponent who can't loses 3 life.
−3: Target creature gets -X/-X until end of turn, where X is the number of cards in your graveyard.
−7: You get an emblem with "At the beginning of combat on your turn, put target creature card from a graveyard onto the battlefield under your control. It gains haste."

Dark Ritual

Tergrid's Lantern

{T}: Target player loses 3 life unless they sacrifice a nonland permanent of their choice or discard a card.
{3}{B}: Untap Tergrid's Lantern.

Tergrid, God of Fright

Menace
Whenever an opponent sacrifices a nontoken permanent or discards a permanent card, you may put that card from a graveyard onto the battlefield under your control.

Tergrid, God of Fright // Tergrid's Lantern

Dreamstealer

Menace
Whenever Dreamstealer deals combat damage to a player, that player discards that many cards.
Eternalize {4}{B}{B} ({4}{B}{B}, Exile this card from your graveyard: Create a token that's a copy of it, except it's a 4/4 black Zombie Human Wizard with no mana cost. Eternalize only as a sorcery.)

Wheel of Torture

At the beginning of each opponent's upkeep, Wheel of Torture deals X damage to that player, where X is 3 minus the number of cards in their hand.

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.

Arcane Signet

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

Megrim

Whenever an opponent discards a card, Megrim deals 2 damage to that player.

Liliana's Caress

Whenever an opponent discards a card, that player loses 2 life.

Arterial Flow

Each opponent discards two cards. If you control a Vampire, each opponent loses 2 life and you gain 2 life.

Inscription of Ruin

Kicker {2}{B}{B}
Choose one. If this spell was kicked, choose any number instead.
• Target opponent discards two cards.
• Return target creature card with mana value 2 or less from your graveyard to the battlefield.
• Destroy target creature with mana value 3 or less.

Syphon Mind

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

Bolas's Citadel

You may look at the top card of your library any time.
You may play lands and cast spells from the top of your library. If you cast a spell this way, pay life equal to its mana value rather than pay its mana cost.
{T}, Sacrifice ten nonland permanents: Each opponent loses 10 life.

Rotting Rats

When Rotting Rats enters, each player discards a card.
Unearth {1}{B} ({1}{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.)

Bojuka Bog

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

Swamp

Cabal Ritual

Add {B}{B}{B}.
Threshold — Add {B}{B}{B}{B}{B} instead if seven or more cards are in your graveyard.

Graveyard Glutton

Ward—Discard a card.
Whenever Graveyard Glutton enters or attacks, exile up to two target cards from graveyards. For each creature card exiled this way, each opponent loses 1 life and you gain 1 life.
Nightbound (If a player casts at least two spells during their own turn, it becomes day next turn.)

Graveyard Trespasser

Ward—Discard a card.
Whenever Graveyard Trespasser enters or attacks, exile up to one target card from a graveyard. If a creature card was exiled this way, each opponent loses 1 life and you gain 1 life.
Daybound (If a player casts no spells during their own turn, it becomes night next turn.)

Graveyard Trespasser // Graveyard Glutton

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.

Delirium Skeins

Awaken the Erstwhile

Each player discards all the cards in their hand, then creates that many 2/2 black Zombie creature tokens.

Necrogen Mists

At the beginning of each player's upkeep, that player discards a card.

Words of Waste

{1}: The next time you would draw a card this turn, each opponent discards a card instead.

Raiders' Wake

Whenever an opponent discards a card, that player loses 2 life.
Raid — At the beginning of your end step, if you attacked this turn, target opponent discards a card.

Rankle, Master of Pranks

Flying, haste
Whenever Rankle, Master of Pranks deals combat damage to a player, choose any number —
• Each player discards a card.
• Each player loses 1 life and draws a card.
• Each player sacrifices a creature of their choice.

Stronghold Rats

Shadow (This creature can block or be blocked by only creatures with shadow.)
Whenever Stronghold Rats deals combat damage to a player, each player discards 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.

Bottomless Pit

At the beginning of each player's upkeep, that player discards a card at random.

Defile

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

Smallpox

Each player loses 1 life, discards a card, sacrifices a creature of their choice, then sacrifices a land of their choice.

Charcoal Diamond

Charcoal Diamond enters tapped.
{T}: Add {B}.

Feed the Swarm

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

Hypnotic Specter

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

Fell Specter

Flying
When Fell Specter enters, target opponent discards a card.
Whenever an opponent discards a card, that player loses 2 life.

Mind Stone

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

Mind Rake

Target player discards two cards.
Overload {1}{B} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Read the Bones

Scry 2, then draw two cards. You lose 2 life. (To scry 2, look at the top two cards of your library, then put any number of them on the bottom and the rest on top in any order.)

Vicious Rumors

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

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.)

Castle Locthwain

Castle Locthwain enters tapped unless you control a Swamp.
{T}: Add {B}.
{1}{B}{B}, {T}: Draw a card, then you lose life equal to the number of cards in your hand.

Raven's Crime

Target player discards a card.
Retrace (You may cast this card from your graveyard by discarding a land card in addition to paying its other costs.)

Stabwhisker the Odious

At the beginning of each opponent's upkeep, that player loses 1 life for each card fewer than three in their hand.

Nezumi Shortfang

{1}{B}, {T}: Target opponent discards a card. Then if that player has no cards in hand, flip Nezumi Shortfang.

Nezumi Shortfang // Stabwhisker the Odious

Force of Despair

If it's not your turn, you may exile a black card from your hand rather than pay this spell's mana cost.
Destroy all creatures that entered this turn.

Tourach, Dread Cantor

Kicker {B}{B} (You may pay an additional {B}{B} as you cast this spell.)
Protection from white
Whenever an opponent discards a card, put a +1/+1 counter on Tourach, Dread Cantor.
When Tourach enters, if it was kicked, target opponent discards two cards at random.

Doom Blade

Dark Deal

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

Dying to Serve

Whenever you discard one or more cards, create a tapped 2/2 black Zombie creature token. This ability triggers only once each turn.

Bag of Holding

Whenever you discard a card, exile that card from your graveyard.
{2}, {T}: Draw a card, then discard a card.
{4}, {T}, Sacrifice Bag of Holding: Return all cards exiled with Bag of Holding to their owner's hand.

Fraying Omnipotence

Each player loses half their life, then discards half the cards in their hand, then sacrifices half the creatures they control of their choice. Round up each time.

Shrieking Affliction

At the beginning of each opponent's upkeep, if that player has one or fewer cards in hand, they lose 3 life.

Necrogoyf

Necrogoyf's power is equal to the number of creature cards in all graveyards.
At the beginning of each player's upkeep, that player discards a card.
Madness {1}{B}{B} (If you discard this card, discard it into exile. When you do, cast it for its madness cost or put it into your graveyard.)

Banshee of the Dread Choir

Myriad (Whenever this creature attacks, for each opponent other than defending player, you may create a token copy that's tapped and attacking that player or a planeswalker they control. Exile the tokens at end of combat.)
Whenever Banshee of the Dread Choir deals combat damage to a player, that player discards a card.

Tinybones, Trinket Thief

At the beginning of each end step, if an opponent discarded a card this turn, you draw a card and you lose 1 life.
{4}{B}{B}: Each opponent with no cards in hand loses 10 life.

Bad Deal

You draw two cards and each opponent discards two cards. Each player loses 2 life.

Cunning Lethemancer

At the beginning of your upkeep, each player discards a card.

Elderfang Disciple

When Elderfang Disciple enters, each opponent discards a card.

Vilis, Broker of Blood

Flying
{B}, Pay 2 life: Target creature gets -1/-1 until end of turn.
Whenever you lose life, draw that many cards. (Damage causes loss of life.)

Sign in Blood

Target player draws two cards and loses 2 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.)

Bone Miser

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

Sol Ring

Mindslicer

When Mindslicer dies, each player discards their hand.

Asylum Visitor

At the beginning of each player's upkeep, if that player has no cards in hand, you draw a card and you lose 1 life.
Madness {1}{B} (If you discard this card, discard it into exile. When you do, cast it for its madness cost or put it into your graveyard.)

Dread Fugue

Cleave {2}{B} (You may cast this spell for its cleave cost. If you do, remove the words in square brackets.)
Target player reveals their hand. You choose a nonland card from it [with mana value 2 or less]. That player discards that card.

Bloodhusk Ritualist

Multikicker {B} (You may pay an additional {B} any number of times as you cast this spell.)
When Bloodhusk Ritualist enters, target opponent discards a card for each time it was kicked.

Davriel, Rogue Shadowmage

At the beginning of each opponent's upkeep, if that player has one or fewer cards in hand, Davriel, Rogue Shadowmage deals 2 damage to them.
−1: Target player discards a card.

Court of Ambition

When Court of Ambition enters, you become the monarch.
At the beginning of your upkeep, each opponent loses 3 life unless they discard a card. If you're the monarch, instead each opponent loses 6 life unless they discard two cards.

Creeping Dread

At the beginning of your upkeep, each player discards a card. Each opponent who discarded a card that shares a card type with the card you discarded loses 3 life. (Players reveal the discarded cards simultaneously.)

Infernal Grasp

Destroy target creature. You lose 2 life.

Plaguecrafter

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

Miasmic Mummy

When Miasmic Mummy enters, each player discards a card.

Archfiend of Ifnir

Flying
Whenever you cycle or discard another card, put a -1/-1 counter on each creature your opponents control.
Cycling {2} ({2}, Discard this card: Draw a card.)

Myojin of Night's Reach

Myojin of Night's Reach enters with a divinity counter on it if you cast it from your hand.
Myojin of Night's Reach has indestructible as long as it has a divinity counter on it.
Remove a divinity counter from Myojin of Night's Reach: Each opponent discards their hand.