Thief of Sanity

Flying
Whenever this creature deals combat damage to a player, look at the top three cards of that player's library, exile one of them face down, then put the rest into their graveyard. You may cast that card for as long as it remains exiled, and mana of any type can be spent to cast that spell.

Bribery

Search target opponent's library for a creature card and put that card onto the battlefield under your control. Then that player shuffles.

Brainstorm

Draw three cards, then put two cards from your hand on top of your library in any order.

Gonti, Lord of Luxury

Deathtouch
When Gonti enters, look at the top four cards of target opponent's library, exile one of them face down, then put the rest on the bottom of that library in a random order. You may cast that card for as long as it remains exiled, and mana of any type can be spent to cast that spell.

Sphinx of the Second Sun

Flying
At the beginning of each of your postcombat main phases, there is an additional beginning phase after this phase. (The beginning phase includes the untap, upkeep, and draw steps.)

Cathartic Adept

Reliquary Tower

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

Delay

Counter target spell. If the spell is countered this way, exile it with three time counters on it instead of putting it into its owner's graveyard. If it doesn't have suspend, it gains suspend. (At the beginning of its owner's upkeep, they remove a time counter. When the last is removed, they may play it without paying its mana cost. If it's a creature, it has haste.)

Hostage Taker

When this creature enters, exile another target creature or artifact until this creature leaves the battlefield. You may cast that card for as long as it remains exiled, and mana of any type can be spent to cast that spell.

Mm'menon, the Right Hand

Flying
You may look at the top card of your library any time.
You may cast artifact spells from the top of your library.
Artifacts you control have "{T}: Add {U}. Spend this mana only to cast a spell from anywhere other than your hand."

Nightveil Specter

Flying
Whenever this creature deals combat damage to a player, that player exiles the top card of their library.
You may play lands and cast spells from among cards exiled with this creature.

Thought Vessel

Infernal Grasp

Destroy target creature. You lose 2 life.

Lightning Greaves

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

Exotic Orchard

{T}: Add one mana of any color that a land an opponent controls could produce.

Underground River

{T}: Add {C}.
{T}: Add {U} or {B}. This land deals 1 damage to you.

Rogue's Passage

{T}: Add {C}.
{4}, {T}: Target creature can't be blocked this turn.

Propaganda

Creatures can't attack you unless their controller pays {2} for each creature they control that's attacking you.

Singularity Rupture

Destroy all creatures, then any number of target players each mill half their library, rounded down.

Extract from Darkness

Each player mills two cards. Then you put a creature card from a graveyard onto the battlefield under your control.

An Offer You Can't Refuse

Counter target noncreature spell. Its controller creates two Treasure tokens. (They're artifacts with "{T}, Sacrifice this token: Add one mana of any color.")

Fallen Shinobi

Ninjutsu {2}{U}{B} ({2}{U}{B}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.)
Whenever this creature deals combat damage to a player, that player exiles the top two cards of their library. Until end of turn, you may play those cards without paying their mana costs.

Xanathar, Guild Kingpin

At the beginning of your upkeep, choose target opponent. Until end of turn, that player can't cast spells, you may look at the top card of their library any time, you may play the top card of their library, and you may spend mana as though it were mana of any color to cast spells this way.

Nephalia Drownyard

{T}: Add {C}.
{1}{U}{B}, {T}: Target player mills three cards.

Swamp

Toxic Deluge

As an additional cost to cast this spell, pay X life.
All creatures get -X/-X until end of turn.

Intellect Devourer

Devour Intellect — When this creature enters, each opponent exiles a card from their hand until this creature leaves the battlefield.
Body Thief — You may play lands and cast spells from among cards exiled with this creature. If you cast a spell this way, you may spend mana as though it were mana of any color to cast it.

Stifle

Counter target activated or triggered ability. (Mana abilities can't be targeted.)

Notion Thief

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.

Negate

Rogue Class

(Gain the next level as a sorcery to add its ability.)
Whenever a creature you control deals combat damage to a player, exile the top card of that player's library face down. You may look at it for as long as it remains exiled.
{1}{U}{B}: Level 2
Creatures you control have menace.
{2}{U}{B}: Level 3
You may play cards exiled with this Class, and you may spend mana as though it were mana of any color to cast those spells.

Drown in the Loch

Choose one —
• Counter target spell with mana value less than or equal to the number of cards in its controller's graveyard.
• Destroy target creature with mana value less than or equal to the number of cards in its controller's graveyard.

Hinder

Counter target spell. If that spell is countered this way, put that card on your choice of the top or bottom of its owner's library instead of into that player's graveyard.

Cunning Rhetoric

Whenever an opponent attacks you and/or one or more planeswalkers you control, exile the top card of that player's library. You may play that card for as long as it remains exiled, and you may spend mana as though it were mana of any color to cast it.

Brainstealer Dragon

Flying
At the beginning of your end step, exile the top card of each opponent's library. You may play those cards for as long as they remain exiled. If you cast a spell this way, you may spend mana as though it were mana of any color to cast it.
Whenever a nonland permanent an opponent owns enters the battlefield under your control, they lose life equal to its mana value.

Duskmantle, House of Shadow

{T}: Add {C}.
{U}{B}, {T}: Target player mills a card.

Memory Plunder

You may cast target instant or sorcery card from an opponent's graveyard without paying its mana cost.

Mind Stone

{T}: Add {C}.
{1}, {T}, Sacrifice this artifact: Draw a card.

Siphon Insight

Look at the top two cards of target opponent's library. Exile one of them face down and put the other on the bottom of that library. You may play the exiled card for as long as it remains exiled, and you may spend mana as though it were mana of any color to cast that spell.
Flashback {1}{U}{B}

Thought Scour

Target player mills two cards.
Draw a card.

Swan Song

Counter target enchantment, instant, or sorcery spell. Its controller creates a 2/2 blue Bird creature token with flying.

Dismal Backwater

This land enters tapped.
When this land enters, you gain 1 life.
{T}: Add {U} or {B}.

Lantern of Insight

Players play with the top card of their libraries revealed.
{T}, Sacrifice this artifact: Target player shuffles.

Shipwreck Marsh

This land enters tapped unless you control two or more other lands.
{T}: Add {U} or {B}.

Choked Estuary

As this land enters, you may reveal an Island or Swamp card from your hand. If you don't, this land enters tapped.
{T}: Add {U} or {B}.

Sunken Hollow

({T}: Add {U} or {B}.)
This land enters tapped unless you control two or more basic lands.

Myriad Landscape

This land enters tapped.
{T}: Add {C}.
{2}, {T}, Sacrifice this land: Search your library for up to two basic land cards that share a land type, put them onto the battlefield tapped, then shuffle.

Counterspell

Paradox Haze

Enchant player
At the beginning of enchanted player's first upkeep each turn, that player gets an additional upkeep step after this step.

Arcane Denial

Counter target spell. Its controller may draw up to two cards at the beginning of the next turn's upkeep.
You draw a card at the beginning of the next turn's upkeep.

Tasha, the Witch Queen

Whenever you cast a spell you don't own, create a 3/3 black Demon creature token.
+1: Draw a card. For each opponent, exile up to one target instant or sorcery card from that player's graveyard and put a page counter on it.
−3: You may cast a spell from among cards in exile with page counters on them without paying its mana cost.
Tasha, the Witch Queen can be your commander.

Bojuka Bog

This land enters tapped.
When this land enters, exile target player's graveyard.
{T}: Add {B}.

Thieving Skydiver

Kicker {X}. X can't be 0. (You may pay an additional {X} as you cast this spell.)
Flying
When this creature enters, if it was kicked, gain control of target artifact with mana value X or less. If that artifact is an Equipment, attach it to this creature.

Portent

Look at the top three cards of target player's library, then put them back in any order. You may have that player shuffle.
Draw a card at the beginning of the next turn's upkeep.

Gríma, Saruman's Footman

Gríma can't be blocked.
Whenever Gríma deals combat damage to a player, that player exiles cards from the top of their library until they exile an instant or sorcery card. You may cast that card without paying its mana cost. Then that player puts the exiled cards that weren't cast this way on the bottom of their library in a random order.

Dark Ritual

Krydle of Baldur's Gate

Whenever Krydle deals combat damage to a player, that player loses 1 life and mills a card, then you gain 1 life and scry 1.
Whenever you attack, you may pay {2}. If you do, target creature can't be blocked this turn.

Memory Lapse

Counter target spell. If that spell is countered this way, put it on top of its owner's library instead of into that player's graveyard.

Telepathy

Your opponents play with their hands revealed.

Tainted Isle

{T}: Add {C}.
{T}: Add {U} or {B}. Activate only if you control a Swamp.

Command Tower

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

Darkwater Catacombs

Reality Shift

Exile target creature. Its controller manifests the top card of their library. (That player puts the top card of their library onto the battlefield face down as a 2/2 creature. If it's a creature card, it can be turned face up any time for its mana cost.)

Blood Money

Destroy all creatures. For each nontoken creature destroyed this way, you create a tapped Treasure token.

Mind Flayer

Dominate Monster — When this creature enters, gain control of target creature for as long as you control this creature.

Baleful Strix

Flying, deathtouch
When this creature enters, draw a card.

Temple of Deceit

This land enters tapped.
When this land enters, scry 1. (Look at the top card of your library. You may put that card on the bottom.)
{T}: Add {U} or {B}.

Dimir Signet

Island

Drowned Catacomb

This land enters tapped unless you control an Island or a Swamp.
{T}: Add {U} or {B}.

Sol Ring

Evil Twin

You may have this creature enter as a copy of any creature on the battlefield, except it has "{U}{B}, {T}: Destroy target creature with the same name as this creature."

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.

Ghoulcaller's Bell

Dimir Aqueduct

This land enters tapped.
When this land enters, return a land you control to its owner's hand.
{T}: Add {U}{B}.

Agent of Treachery

When this creature enters, gain control of target permanent.
At the beginning of your end step, if you control three or more permanents you don't own, draw three cards.

Elder Brain

Menace
Whenever this creature attacks a player, exile all cards from that player's hand, then they draw that many cards. You may play lands and cast spells from among the exiled cards for as long as they remain exiled. If you cast a spell this way, you may spend mana as though it were mana of any color to cast it.

Go for the Throat

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.)

Arcane Signet

Feed the Swarm

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

Lazav, Dimir Mastermind

Hexproof
Whenever a creature card is put into an opponent's graveyard from anywhere, you may have Lazav become a copy of that card, except its name is Lazav, Dimir Mastermind, it's legendary in addition to its other types, and it has hexproof and this ability.

Codex Shredder

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

Fetid Pools

({T}: Add {U} or {B}.)
This land enters tapped.
Cycling {2} ({2}, Discard this card: Draw a card.)