Glimpse the Unthinkable

Watery Grave

({T}: Add {U} or {B}.)
As Watery Grave enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.

Relic of Legends

{T}: Add one mana of any color.
Tap an untapped legendary creature you control: Add one mana of any color.

Sphinx Mindbreaker

Flying
When Sphinx Mindbreaker enters the battlefield, each opponent mills ten cards.

Fractured Sanity

Each opponent mills fourteen cards.
Cycling {1}{U} ({1}{U}, Discard this card: Draw a card.)
When you cycle Fractured Sanity, each opponent mills four cards.

Command Tower

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

Anticognition

Counter target creature or planeswalker spell unless its controller pays {2}. If an opponent has eight or more cards in their graveyard, instead counter that spell, then scry 2.

Ruin Crab

Landfall — Whenever a land enters the battlefield under your control, each opponent mills three cards. (To mill a card, a player puts the top card of their library into their graveyard.)

Heraldic Banner

As Heraldic Banner enters the battlefield, choose a color.
Creatures you control of the chosen color get +1/+0.
{T}: Add one mana of the chosen color.

Ravenform

Exile target artifact or creature. Its controller creates a 1/1 blue Bird creature token with flying.
Foretell {U} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)

Aetherize

Return all attacking creatures to their owner's hand.

Drowned Secrets

Whenever you cast a blue spell, target player mills two cards.

Soaring Thought-Thief

Flash
Flying
As long as an opponent has eight or more cards in their graveyard, Rogues you control get +1/+0.
Whenever one or more Rogues you control attack, each opponent mills two cards.

Dimir Signet

Submerged Boneyard

Submerged Boneyard enters the battlefield tapped.
{T}: Add {U} or {B}.

Zulaport Duelist

Flash
When Zulaport Duelist enters the battlefield, up to one target creature gets -2/-0 until end of turn. Its controller mills two cards. (They put the top two cards of their library into their graveyard.)

Jace, Memory Adept

+1: Draw a card. Target player mills a card.
0: Target player mills ten cards.
−7: Any number of target players each draw twenty cards.

Mistvault Bridge

Mistvault Bridge enters the battlefield tapped.
Indestructible
{T}: Add {U} or {B}.

Dimir Aqueduct

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}.

Leyline of the Void

If Leyline of the Void is in your opening hand, you may begin the game with it on the battlefield.
If a card would be put into an opponent's graveyard from anywhere, exile it instead.

Mesmeric Orb

Whenever a permanent becomes untapped, that permanent's controller mills a card.

Thieves' Guild Enforcer

Flash
Whenever Thieves' Guild Enforcer or another Rogue enters the battlefield under your control, each opponent mills two cards.
As long as an opponent has eight or more cards in their graveyard, Thieves' Guild Enforcer gets +2/+1 and has deathtouch.

Stream of Thought

Target player mills four cards. You shuffle up to four cards from your graveyard into your library.
Replicate {2}{U}{U} (When you cast this spell, copy it for each time you paid its replicate cost. You may choose new targets for the copies.)

Traumatize

Target player mills half their library, rounded down.

Pharika's Libation

Choose one —
• Target opponent sacrifices a creature.
• Target opponent sacrifices an enchantment.

Drowned Catacomb

Drowned Catacomb enters the battlefield tapped unless you control an Island or a Swamp.
{T}: Add {U} or {B}.

Dismal Backwater

Dismal Backwater enters the battlefield tapped.
When Dismal Backwater enters the battlefield, you gain 1 life.
{T}: Add {U} or {B}.

Mirko Vosk, Mind Drinker

Flying
Whenever Mirko Vosk, Mind Drinker deals combat damage to a player, that player reveals cards from the top of their library until they reveal four land cards, then puts those cards into their graveyard.

Temple of Deceit

Temple of Deceit enters the battlefield tapped.
When Temple of Deceit enters the battlefield, scry 1.
{T}: Add {U} or {B}.

Didn't Say Please

Counter target spell. Its controller mills three cards.

Ashiok, Dream Render

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.

Arcane Signet

Teferi's Tutelage

When Teferi's Tutelage enters the battlefield, draw a card, then discard a card.
Whenever you draw a card, target opponent mills two cards. (They put the top two cards of their library into their graveyard.)

Forced Fruition

Whenever an opponent casts a spell, that player draws seven cards.

Hero's Downfall

Maddening Cacophony

Kicker {3}{U}
Each opponent mills eight cards. If this spell was kicked, instead each opponent mills half their library, rounded up.

Keep Safe

Counter target spell that targets a permanent you control.
Draw a card.

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.)

Commander's Sphere

{T}: Add one mana of any color in your commander's color identity.
Sacrifice Commander's Sphere: Draw a card.

Keening Stone

{5}, {T}: Target player mills X cards, where X is the number of cards in that player's graveyard.

Hedron Crab

Landfall — Whenever a land enters the battlefield under your control, target player mills three cards.

Altar of Dementia

Sacrifice a creature: Target player mills cards equal to the sacrificed creature's power.

Drown in Dreams

Choose one. If you control a commander as you cast this spell, you may choose both.
• Target player draws X cards.
• Target player mills twice X cards.

Enter the God-Eternals

Enter the God-Eternals deals 4 damage to target creature and you gain life equal to the damage dealt this way. Target player mills four cards. Amass Zombies 4. (Put four +1/+1 counters on an Army you control. It's also a Zombie. If you don't control an Army, create a 0/0 black Zombie Army creature token first.)

Sunken Hollow

({T}: Add {U} or {B}.)
Sunken Hollow enters the battlefield tapped unless you control two or more basic lands.

Charcoal Diamond

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

Swamp

Nephalia Drownyard

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

Bojuka Bog

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

Cut Your Losses

Casualty 2 (As you cast this spell, you may sacrifice a creature with power 2 or greater. When you do, copy this spell and you may choose a new target for the copy.)
Target player mills half their library, rounded down.

War Room

{T}: Add {C}.
{3}, {T}, Pay life equal to the number of colors in your commanders' color identity: Draw a card.

Negate

Phenax, God of Deception

Indestructible
As long as your devotion to blue and black is less than seven, Phenax isn't a creature.
Creatures you control have "{T}: Target player mills X cards, where X is this creature's toughness."

Persistent Nightmare

Skulk (This creature can't be blocked by creatures with greater power.)
When Persistent Nightmare deals combat damage to a player, return it to its owner's hand.

Startled Awake

Target opponent mills thirteen cards.
{3}{U}{U}: Put Startled Awake from your graveyard onto the battlefield transformed. Activate only as a sorcery.

Startled Awake // Persistent Nightmare

Sky Diamond

Sky Diamond enters the battlefield tapped.
{T}: Add {U}.

Oona, Queen of the Fae

Flying
{X}{U/B}: Choose a color. Target opponent exiles the top X cards of their library. For each card of the chosen color exiled this way, create a 1/1 blue and black Faerie Rogue creature token with flying.

Mind Stone

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

Dimir Guildgate

Dimir Guildgate enters the battlefield tapped.
{T}: Add {U} or {B}.

Merfolk Windrobber

Flying
Whenever Merfolk Windrobber deals combat damage to a player, that player mills a card. (They put the top card of their library into their graveyard.)
Sacrifice Merfolk Windrobber: Draw a card. Activate only if an opponent has eight or more cards in their graveyard.

Feed the Swarm

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

Ponder

Look at the top three cards of your library, then put them back in any order. You may shuffle.
Draw a card.

Riddlekeeper

Whenever a creature attacks you or a planeswalker you control, that creature's controller mills two cards.

Wight of Precinct Six

Wight of Precinct Six gets +1/+1 for each creature card in your opponents' graveyards.

Sol Ring

Consuming Aberration

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.

Fleet Swallower

Whenever Fleet Swallower attacks, target player mills half their library, rounded up.

Bruvac the Grandiloquent

If an opponent would mill one or more cards, they mill twice that many cards instead. (To mill a card, a player puts the top card of their library into their graveyard.)

Thought Scour

Target player mills two cards.
Draw a card.

Island

Unseal the Necropolis

Each player mills three cards. Then you return up to two creature cards from your graveyard to your hand. (To mill three cards, a player puts the top three cards of their library into their graveyard.)

Anowon, the Ruin Thief

Other Rogues you control get +1/+1.
Whenever one or more Rogues you control deal combat damage to a player, that player mills a card for each 1 damage dealt to them. If the player mills at least one creature card this way, you draw a card. (To mill a card, a player puts the top card of their library into their graveyard.)

Mana Geode

When Mana Geode enters the battlefield, scry 1.
{T}: Add one mana of any color.

Nemesis of Reason

Whenever Nemesis of Reason attacks, defending player mills ten cards.

Psychic Corrosion

Whenever you draw a card, each opponent mills two cards.

Mind Funeral

Target opponent reveals cards from the top of their library until four land cards are revealed. That player puts all cards revealed this way into their graveyard.

Evolving Wilds

{T}, Sacrifice Evolving Wilds: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.