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.

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.

Cabal Stronghold

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

Demonic Tutor

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

Torment of Hailfire

Repeat the following process X times. Each opponent loses 3 life unless that player sacrifices a nonland permanent of their choice or 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.

Virus Beetle

When Virus Beetle enters, each opponent discards 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 tapped.
When Bojuka Bog enters, exile target player's graveyard.
{T}: Add {B}.

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.

Crucible of Worlds

Plaguecrafter

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

Mutilate

All creatures get -1/-1 until end of turn for each Swamp you control.

Bad Deal

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

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.

From Under the Floorboards

Madness {X}{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.)
Create three tapped 2/2 black Zombie creature tokens and you gain 3 life. If this spell's madness cost was paid, instead create X of those tokens and you gain X life.

Oppression

Whenever a player casts a spell, that player discards a card.

Fell Specter

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

Arcane Signet

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

Deadly Rollick

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

Swamp

Jet Medallion

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

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.

Sheoldred's Edict

Choose one —
• Each opponent sacrifices a nontoken creature of their choice.
• Each opponent sacrifices a creature token of their choice.
• Each opponent sacrifices a planeswalker of their choice.

Call to the Netherworld

Return target black creature card from your graveyard to your hand.
Madness {0} (If you discard this card, discard it into exile. When you do, cast it for its madness cost or put it into your graveyard.)

Liliana's Caress

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

Geier Reach Sanitarium

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

Geth's Grimoire

Whenever an opponent discards a card, you may draw a card.

Peer into the Abyss

Target player draws cards equal to half the number of cards in their library and loses half their life. Round up each time.

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 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.

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.)

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.

Accursed Marauder

When Accursed Marauder enters, each player sacrifices a nontoken creature of their choice.

Painful Quandary

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

Dark Deal

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

Feast of Sanity

Whenever you discard a card, Feast of Sanity deals 1 damage to any target and you gain 1 life.

Reanimate

Put target creature card from a graveyard onto the battlefield under your control. You lose life equal to its mana value.

Big Game Hunter

When Big Game Hunter enters, destroy target creature with power 4 or greater. It can't be regenerated.
Madness {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.)

Bottomless Pit

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

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}.

Delirium Skeins

Village Rites

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

Lightning Greaves

Equipped creature has haste and shroud. (It can't be the target of spells or abilities.)
Equip {0}

Dark Ritual

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.)

Vampiric Tutor

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

Refurbished Familiar

Affinity for artifacts (This spell costs {1} less to cast for each artifact you control.)
Flying
When Refurbished Familiar enters, each opponent discards a card. For each opponent who can't, you draw a card.

Hymn to Tourach

Target player discards two cards at random.

Infernal Grasp

Destroy target creature. You lose 2 life.

Greel, Mind Raker

{X}{B}, {T}, Discard two cards: Target player discards X cards at random.

The Raven Man

At the beginning of each end step, if a player discarded a card this turn, create a 1/1 black Bird creature token with flying and "This creature can't block."
{3}{B}, {T}: Each opponent discards a card. Activate only as a sorcery.

Thought Vessel

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

The Eldest Reborn

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Each opponent sacrifices a creature or planeswalker of their choice.
II — Each opponent discards a card.
III — Put target creature or planeswalker card from a graveyard onto the battlefield under your control.

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.

Sign in Blood

Target player draws two cards and loses 2 life.

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.

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."

Solemn Simulacrum

When this creature enters, you may search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.
When this creature dies, you may draw a card.

Liliana of the Veil

+1: Each player discards a card.
−2: Target player sacrifices a creature.
−6: Separate all permanents target player controls into two piles. That player sacrifices all permanents in the pile of their choice.

Megrim

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

Duress

Target opponent reveals their hand. You choose a noncreature, nonland card from it. That player discards that card.

Swiftfoot Boots

Equipped creature has hexproof and haste. (It can't be the target of spells or abilities your opponents control. It can attack and {T} no matter when it came under your control.)
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Charcoal Diamond

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

Shrieking Affliction

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