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.)
2 /
2
{2}{B}{B}
Abyssal Specter
Creature - Specter
Flying
Whenever Abyssal Specter deals damage to a player, that player discards a card.
2 /
3
{3}{U}
Aetherize
Instant
Return all attacking creatures to their owner's hand.
{3}{U}{U}
Aetherspouts
Instant
For each attacking creature, its owner puts it on the top or bottom of their library.
{1}{U/B}{U/B}
Ashiok, Dream Render
Legendary Planeswalker - Ashiok
Spells and abilities your opponents control can't cause their controller to search their library.
-1: Target player mills four cards. Then exile each opponent's graveyard.
L:
5
{3}{B}{B}
Banshee of the Dread Choir
Creature - Spirit
Myriad (Whenever this creature attacks, for each opponent other than defending player, you may create a token that's a copy of this creature 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.
4 /
4
{5}
Bargaining Table
Artifact
{X}, {T}: Draw a card. X is the number of cards in an opponent's hand.
{2}{U}{B}
Barrin's Spite
Sorcery
Choose two target creatures controlled by the same player. Their controller chooses and sacrifices one of them. Return the other to its owner's hand.
{2}
Charcoal Diamond
Artifact
Charcoal Diamond enters the battlefield tapped.
{T}: Add {B}.
--
Choked Estuary
Land
As Choked Estuary enters the battlefield, you may reveal an Island or Swamp card from your hand. If you don't, Choked Estuary enters the battlefield tapped.
{T}: Add {U} or {B}.
{2}
Coldsteel Heart
Snow Artifact
Coldsteel Heart enters the battlefield tapped.
As Coldsteel Heart enters the battlefield, choose a color.
{T}: Add one mana of the chosen color.
--
Command Tower
Land
{T}: Add one mana of any color in your commander's color identity.
{3}
Commander's Sphere
Artifact
{T}: Add one mana of any color in your commander's color identity.
Sacrifice Commander's Sphere: Draw a card.
{3}{U}{B}
Consuming Aberration
Creature - Horror
Consuming Aberration's power and toughness are each equal to the number of cards in your opponents' graveyards.
Whenever you cast a spell, each opponent reveals cards from the top of their library until they reveal a land card, then puts those cards into their graveyard.
* /
*
--
Coral Atoll
Land
Coral Atoll enters the battlefield tapped.
When Coral Atoll enters the battlefield, sacrifice it unless you return an untapped Island you control to its owner's hand.
{T}: Add {C}{U}.
{4}
Cursed Rack
Artifact
As Cursed Rack enters the battlefield, choose an opponent.
The chosen player's maximum hand size is four.
{2}{B}
Dark Deal
Sorcery
Each player discards all the cards in their hand, then draws that many cards minus one.
{B}
Dark Ritual
Instant
Add {B}{B}{B}.
--
Darkwater Catacombs
Land
{1}, {T}: Add {U}{B}.
--
Dimir Aqueduct
Land
Dimir Aqueduct enters the battlefield tapped.
When Dimir Aqueduct enters the battlefield, return a land you control to its owner's hand.
{T}: Add {U}{B}.
{1}{U}{B}
Dimir Cutpurse
Creature - Spirit
Whenever Dimir Cutpurse deals combat damage to a player, that player discards a card and you draw a card.
2 /
2
--
Dimir Guildgate
Land - Gate
Dimir Guildgate enters the battlefield tapped.
{T}: Add {U} or {B}.
{2}
Dimir Signet
Artifact
{1}, {T}: Add {U}{B}.
{3}{U/B}{U/B}
Dire Undercurrents
Enchantment
Whenever a blue creature enters the battlefield under your control, you may have target player draw a card.
Whenever a black creature enters the battlefield under your control, you may have target player discard a card.
{U/B}
Dream Salvage
Instant
Draw cards equal to the number of cards target opponent discarded this turn.
{U}{B}
Duskmantle Guildmage
Creature - Human Wizard
{1}{U}{B}: Whenever a card is put into an opponent's graveyard from anywhere this turn, that player loses 1 life.
{2}{U}{B}: Target player mills two cards.
2 /
2
--
Duskmantle, House of Shadow
Land
{T}: Add {C}.
{U}{B}, {T}: Target player mills a card.
--
Everglades
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}.
--
Evolving Wilds
Land
{T}, Sacrifice Evolving Wilds: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.
{3}{B}
Fell Specter
Creature - Specter
Flying
When Fell Specter enters the battlefield, target opponent discards a card.
Whenever an opponent discards a card, that player loses 2 life.
1 /
3
--
Field of Ruin
Land
{T}: Add {C}.
{2}, {T}, Sacrifice Field of Ruin: Destroy target nonbasic land an opponent controls. Each player searches their library for a basic land card, puts it onto the battlefield, then shuffles.
--
Forbidden Orchard
Land
{T}: Add one mana of any color.
Whenever you tap Forbidden Orchard for mana, target opponent creates a 1/1 colorless Spirit creature token.
--
Geier Reach Sanitarium
Legendary Land
{T}: Add {C}.
{2}, {T}: Each player draws a card, then discards a card.
{4}
Geth's Grimoire
Artifact
Whenever an opponent discards a card, you may draw a card.
--
Ghost Quarter
Land
{T}: Add {C}.
{T}, Sacrifice Ghost Quarter: Destroy target land. Its controller may search their library for a basic land card, put it onto the battlefield, then shuffle.
{1}
Glasses of Urza
Artifact
{T}: Look at target player's hand.
--
Grixis Panorama
Land
{T}: Add {C}.
{1}, {T}, Sacrifice Grixis Panorama: Search your library for a basic Island, Swamp, or Mountain card, put it onto the battlefield tapped, then shuffle.
{5}{B}{B}
Hollowborn Barghest
Creature - Demon Dog
At the beginning of your upkeep, if you have no cards in hand, each opponent loses 2 life.
At the beginning of each opponent's upkeep, if that player has no cards in hand, they lose 2 life.
7 /
6
{B}{B}
Hymn to Tourach
Sorcery
Target player discards two cards at random.
{1}{B}{B}
Hypnotic Specter
Creature - Specter
Flying
Whenever Hypnotic Specter deals damage to an opponent, that player discards a card at random.
2 /
2
--
Island
Basic Land - Island
({T}: Add {U}.)
--
Island
Basic Land - Island
({T}: Add {U}.)
--
Island
Basic Land - Island
({T}: Add {U}.)
--
Island
Basic Land - Island
({T}: Add {U}.)
--
Island
Basic Land - Island
({T}: Add {U}.)
--
Island
Basic Land - Island
({T}: Add {U}.)
--
Island
Basic Land - Island
({T}: Add {U}.)
--
Island
Basic Land - Island
({T}: Add {U}.)
--
Island
Basic Land - Island
({T}: Add {U}.)
{1}
Library of Leng
Artifact
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.
{1}{B}
Liliana's Caress
Enchantment
Whenever an opponent discards a card, that player loses 2 life.
{1}
Mana Vault
Artifact
Mana Vault doesn't untap during your untap step.
At the beginning of your upkeep, you may pay {4}. If you do, untap Mana Vault.
At the beginning of your draw step, if Mana Vault is tapped, it deals 1 damage to you.
{T}: Add {C}{C}{C}.
{2}{B}
Megrim
Enchantment
Whenever an opponent discards a card, Megrim deals 2 damage to that player.
{U}
Mind Bomb
Sorcery
Each player may discard up to three cards. Mind Bomb deals damage to each player equal to 3 minus the number of cards they discarded this way.
{X}{B}
Mind Twist
Sorcery
Target player discards X cards at random.
{1}{U}{B}
Mnemonic Betrayal
Sorcery
Exile all opponents' graveyards. You may cast spells from among those cards this turn, and you may spend mana as though it were mana of any type to cast those spells. At the beginning of the next end step, if any of those cards remain exiled, return them to their owners' graveyards.
Exile Mnemonic Betrayal.
{U}
Mystic Remora
Enchantment
Cumulative upkeep {1} (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)
Whenever an opponent casts a noncreature spell, you may draw a card unless that player pays {4}.
{1}{U}{U}
Narset, Parter of Veils
Legendary Planeswalker - Narset
Each opponent can't draw more than one card each turn.
-2: Look at the top four cards of your library. You may reveal a noncreature, nonland card from among them and put it into your hand. Put the rest on the bottom of your library in a random order.
L:
5
{3}{U}{B}
Nebuchadnezzar
Legendary Creature - Human Wizard
{X}, {T}: Choose a card name. Target opponent reveals X cards at random from their hand. Then that player discards all cards with that name revealed this way. Activate only during your turn.
3 /
3
{1}{B}
Nezumi Shortfang
Creature - Rat Rogue
{1}{B}, {T}: Target opponent discards a card. Then if that player has no cards in hand, flip Nezumi Shortfang.
1 /
1
--
Stabwhisker the Odious
Legendary Creature - Rat Shaman
At the beginning of each opponent's upkeep, that player loses 1 life for each card fewer than three in their hand.
1 /
1
{1}
Nihil Spellbomb
Artifact
{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.
{4}
Noetic Scales
Artifact
At the beginning of each player's upkeep, return to its owner's hand each creature that player controls with power greater than the number of cards in their hand.
{2}{U}{B}
Notion Thief
Creature - Human Rogue
Flash
If an opponent would draw a card except the first one they draw in each of their draw steps, instead that player skips that draw and you draw a card.
3 /
1
{1}{B}{B}
Nyxathid
Creature - Elemental
As Nyxathid enters the battlefield, choose an opponent.
Nyxathid gets -1/-1 for each card in the chosen player's hand.
7 /
7
{3}{B}{B}
Ob Nixilis, the Hate-Twisted
Legendary Planeswalker - Nixilis
Whenever an opponent draws a card, Ob Nixilis, the Hate-Twisted deals 1 damage to that player.
-2: Destroy target creature. Its controller draws two cards.
L:
5
{3}
Paupers' Cage
Artifact
At the beginning of each opponent's upkeep, if that player has two or fewer cards in hand, Paupers' Cage deals 2 damage to that player.
{1}{U}{B}
Perplex
Instant
Counter target spell unless its controller discards their hand.
Transmute {1}{U}{B} ({1}{U}{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.)
{2}{U}
Planeswalker's Mischief
Enchantment
{3}{U}: Target opponent reveals a card at random from their hand. If it's an instant or sorcery card, exile it. You may cast it without paying its mana cost for as long as it remains exiled. At the beginning of the next end step, if you haven't cast it, return it to its owner's hand. Activate only as a sorcery.
{1}{U}{B}
Psychic Strike
Instant
Counter target spell. Its controller mills two cards.
{B}
Quest for the Nihil Stone
Enchantment
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.
{4}
Rackling
Artifact Creature - Phyrexian Construct
At the beginning of each opponent's upkeep, Rackling deals X damage to that player, where X is 3 minus the number of cards in their hand.
2 /
2
{2}{B}{B}
Rag Man
Creature - Human Minion
{B}{B}{B}, {T}: Target opponent reveals their hand and discards a creature card at random. Activate only during your turn.
2 /
1
{3}{B}
Raiders' Wake
Enchantment
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.
{4}{U}{U}
River's Rebuke
Sorcery
Return all nonland permanents target player controls to their owner's hand.
--
Rogue's Passage
Land
{T}: Add {C}.
{4}, {T}: Target creature can't be blocked this turn.
{2}{B}{B}
Sangromancer
Creature - Vampire Shaman
Flying
Whenever a creature an opponent controls dies, you may gain 3 life.
Whenever an opponent discards a card, you may gain 3 life.
3 /
3
{4}{B}{B}
Scythe Specter
Creature - Specter
Flying
Whenever Scythe Specter deals combat damage to a player, each opponent discards a card. Each player who discarded a card with the highest mana value among cards discarded this way loses life equal to that mana value.
4 /
4
{1}
Sensei's Divining Top
Artifact
{1}: Look at the top three cards of your library, then put them back in any order.
{T}: Draw a card, then put Sensei's Divining Top on top of its owner's library.
{B}
Shrieking Affliction
Enchantment
At the beginning of each opponent's upkeep, if that player has one or fewer cards in hand, they lose 3 life.
{1}{U}{B}
Siren of the Silent Song
Creature - Zombie Siren
Flying
Inspired -- Whenever Siren of the Silent Song becomes untapped, each opponent discards a card, then each opponent mills a card.
2 /
1
{4}
Skullcage
Artifact
At the beginning of each opponent's upkeep, Skullcage deals 2 damage to that player unless they have exactly three or exactly four cards in hand.
{1}
Sol Ring
Artifact
{T}: Add {C}{C}.
{2}{B}
Stronghold Rats
Creature - Rat
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.
2 /
1
--
Swamp
Basic Land - Swamp
({T}: Add {B}.)
--
Swamp
Basic Land - Swamp
({T}: Add {B}.)
--
Swamp
Basic Land - Swamp
({T}: Add {B}.)
--
Swamp
Basic Land - Swamp
({T}: Add {B}.)
--
Swamp
Basic Land - Swamp
({T}: Add {B}.)
--
Swamp
Basic Land - Swamp
({T}: Add {B}.)
--
Swamp
Basic Land - Swamp
({T}: Add {B}.)
--
Swamp
Basic Land - Swamp
({T}: Add {B}.)
--
Swamp
Basic Land - Swamp
({T}: Add {B}.)
--
Swamp
Basic Land - Swamp
({T}: Add {B}.)
{3}{B}
Syphon Mind
Sorcery
Each other player discards a card. You draw a card for each card discarded this way.
{2}
Talisman of Dominance
Artifact
{T}: Add {C}.
{T}: Add {U} or {B}. Talisman of Dominance deals 1 damage to you.
{U}
Telepathy
Enchantment
Your opponents play with their hands revealed.
--
Temple of Deceit
Land
Temple of Deceit enters the battlefield tapped.
When Temple of Deceit enters the battlefield, scry 1.
{T}: Add {U} or {B}.
--
Terramorphic Expanse
Land
{T}, Sacrifice Terramorphic Expanse: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.
{4}{B}
The Eldest Reborn
Enchantment - Saga
(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I -- Each opponent sacrifices a creature or planeswalker.
II -- Each opponent discards a card.
III -- Put target creature or planeswalker card from a graveyard onto the battlefield under your control.
{4}{B}{B}
The Haunt of Hightower
Legendary Creature - Vampire
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.
3 /
3
{1}
The Rack
Artifact
As The Rack enters the battlefield, choose an opponent.
At the beginning of the chosen player's upkeep, The Rack deals X damage to that player, where X is 3 minus the number of cards in their hand.
{2}
Thought Vessel
Artifact
You have no maximum hand size.
{T}: Add {C}.
{U}{B}
Thoughtcutter Agent
Artifact Creature - Human Rogue
{U}{B}, {T}: Target player loses 1 life and reveals their hand.
{T}: Add {U} or {B}. Underground River deals 1 damage to you.
{3}{B}
Unnerve
Sorcery
Each opponent discards two cards.
{4}{B}{B}
Urgoros, the Empty One
Legendary Creature - Specter
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.
4 /
3
{4}
Vedalken Orrery
Artifact
You may cast spells as though they had flash.
{2}{U}
Wandering Eye
Creature - Illusion
Flying
Players play with their hands revealed.
1 /
3
{1}{B}
Waste Not
Enchantment
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.
--
Waterveil Cavern
Land
{T}: Add {C}.
{T}: Add {U} or {B}. Waterveil Cavern doesn't untap during your next untap step.
{1}
Wayfarer's Bauble
Artifact
{2}, {T}, Sacrifice Wayfarer's Bauble: Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.
{3}
Wheel of Torture
Artifact
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.
{2}{U}
Windfall
Sorcery
Each player discards their hand, then draws cards equal to the greatest number of cards a player discarded this way.
{3}{U}
Zur's Weirding
Enchantment
Players play with their hands revealed.
If a player would draw a card, they reveal it instead. Then any other player may pay 2 life. If a player does, put that card into its owner's graveyard. Otherwise, that player draws a card.
{3}{U}{U}{U}
Amnesia
Sorcery
Target player reveals their hand and discards all nonland cards.
{2}{B}
Dreamstealer
Creature - Human Wizard
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.)
1 /
2
{3}{U/B}
Helm of the Ghastlord
Enchantment - Aura
Enchant creature
As long as enchanted creature is blue, it gets +1/+1 and has "Whenever this creature deals damage to an opponent, draw a card."
As long as enchanted creature is black, it gets +1/+1 and has "Whenever this creature deals damage to an opponent, that player discards a card."
{3}{B}{B}
Painful Quandary
Enchantment
Whenever an opponent casts a spell, that player loses 5 life unless they discard a card.
{1}{U}{B}
Recoil
Instant
Return target permanent to its owner's hand. Then that player discards a card.
{2}{U}{B}
Seer's Vision
Enchantment
Your opponents play with their hands revealed.
Sacrifice Seer's Vision: Look at target player's hand and choose a card from it. That player discards that card. Activate only as a sorcery.