Whenever an opponent discards a card, Abyssal Nocturnus gets +2/+2 and gains fear until end of turn. (It can't be blocked except by artifact creatures and/or black creatures.)

Flying

Whenever Abyssal Specter deals damage to a player, that player discards a card.

{1}{B}: Regenerate Augur of Skulls.

Sacrifice Augur of Skulls: Target player discards two cards. Activate only during your upkeep.

Barren Moor enters the battlefield tapped.

{T}: Add {B}.

Cycling {B} ({B}, Discard this card: Draw a card.)

Multikicker {B} (You may pay an additional {B} any number of times as you cast this spell.)

When Bloodhusk Ritualist enters the battlefield, target opponent discards a card for each time it was kicked.

{B}, {T}, Discard a card: Add {B}{B}{B}.

Until end of turn, whenever a player taps a Swamp for mana, that player adds an additional {B}.

Threshold -- {1}{B}, {T}, Exile two cards from your graveyard: Target player discards a card. Activate only as a sorcery and only if seven or more cards are in your graveyard.

Add {B}{B}{B}.

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

{T}: Add {C}.

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

{T}: Target opponent discards two cards. Activate only during your turn, before attackers are declared.

When Court of Ambition enters the battlefield, 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.

Target player discards a card.

Haunt (When this spell card is put into a graveyard after resolving, exile it haunting target creature.)

When the creature Cry of Contrition haunts dies, target player discards a card.

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

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

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.

Ebon Stronghold enters the battlefield tapped.

{T}: Add {B}.

{T}, Sacrifice Ebon Stronghold: Add {B}{B}.

{T}: Add {C}.

{1}, {T}, Sacrifice Emergence Zone: You may cast spells this turn as though they had flash.

{T}: Add {C}.

{4}, {T}, Sacrifice Encroaching Wastes: Destroy target nonbasic land.

Everglades enters the battlefield tapped.

When Everglades enters the battlefield, sacrifice it unless you return an untapped Swamp you control to its owner's hand.

{T}: Add {C}{B}.

Flying

When Fell Specter enters the battlefield, target opponent discards a card.

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

{T}: Add {C}.

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

{4}{B}, {T}: Target player discards two cards. Activate only as a sorcery.

Channel -- {5}{B}{B}, Discard Ghost-Lit Stalker: Target player discards four cards. Activate only as a sorcery.

Target player discards two cards at random.

Flying

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

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

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

Target player discards two cards.

Overload {1}{B} (You may cast this spell for its overload cost. If you do, change its text by replacing all instances of "target" with "each.")

Target player discards X cards at random.

Target player discards a card for each Swamp you control.

Target player discards X cards at random.

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

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

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

Magecraft -- Whenever you cast or copy an instant or sorcery spell, each opponent loses 2 life and you gain 2 life.

+1: You lose 1 life. Look at the top three cards of your library. Put one of them into your hand and the rest into your graveyard.

-3: Each opponent sacrifices a creature with the greatest power among creatures that player controls.

-8: Each opponent may discard a card. If they don't, they lose 3 life. Repeat this process six more times.

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.

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.

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.)

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

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

({T}: Add {B}.)

({T}: Add {B}.)

({T}: Add {B}.)

({T}: Add {B}.)

({T}: Add {B}.)

({T}: Add {B}.)

({T}: Add {B}.)

({T}: Add {B}.)

({T}: Add {B}.)

({T}: Add {B}.)

({T}: Add {B}.)

({T}: Add {B}.)

({T}: Add {B}.)

({T}: Add {B}.)

({T}: Add {B}.)

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.

{T}: Target player loses 3 life unless they sacrifice a nonland permanent or discard a card.

{3}{B}: Untap Tergrid's Lantern.

Flying, lifelink

Whenever The Haunt of Hightower attacks, defending player discards a card.

Whenever a card is put into an opponent's graveyard from anywhere, put a +1/+1 counter on The Haunt of Hightower.

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.

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

Flying

Whenever Urgoros, the Empty One deals combat damage to a player, that player discards a card at random. If the player can't, you draw a card.

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.