Inspiration from Beyond

Mill three cards, then return an instant or sorcery card from your graveyard to your hand.
Flashback {5}{U}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

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.

Flow of Knowledge

Draw a card for each Island you control, then discard two cards.

Fascination

Choose one —
• Each player draws X cards.
• Each player mills X cards.

Dampen Thought

Target player mills four cards.
Splice onto Arcane {1}{U} (As you cast an Arcane spell, you may reveal this card from your hand and pay its splice cost. If you do, add this card's effects to that spell.)

Winter Moon

Players can't untap more than one nonbasic land during their untap steps.

Treasure Cruise

Delve (Each card you exile from your graveyard while casting this spell pays for {1}.)
Draw three cards.

Jace's Erasure

Whenever you draw a card, you may have target player mill a card.

Manic Scribe

When Manic Scribe enters, each opponent mills three cards.
Delirium — At the beginning of each opponent's upkeep, if there are four or more card types among cards in your graveyard, that player mills three cards.

Thought Scour

Target player mills two cards.
Draw a card.

Archive Trap

If an opponent searched their library this turn, you may pay {0} rather than pay this spell's mana cost.
Target opponent mills thirteen cards.

Thought Collapse

Counter target spell. Its controller mills three cards.

The Mindskinner

The Mindskinner can't be blocked.
If a source you control would deal damage to an opponent, prevent that damage and each opponent mills that many cards.

Bond of Insight

Each player mills four cards. Return up to two instant and/or sorcery cards from your graveyard to your hand. Exile Bond of Insight.

Compelling Argument

Target player mills five cards.
Cycling {U} ({U}, Discard this card: Draw a card.)

Midnight Clock

{T}: Add {U}.
{2}{U}: Put an hour counter on Midnight Clock.
At the beginning of each upkeep, put an hour counter on Midnight Clock.
When the twelfth hour counter is put on Midnight Clock, shuffle your hand and graveyard into your library, then draw seven cards. Exile Midnight Clock.

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.

Teferi's Tutelage

When Teferi's Tutelage enters, 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.)

Island

Heed the Mists

Mill a card, then draw cards equal to the milled card's mana value.

Fear of Death

Enchant creature
When Fear of Death enters, mill two cards. (Put the top two cards of your library into your graveyard.)
Enchanted creature gets -X/-0, where X is the number of cards in your graveyard.

Flow of Ideas

Talrand, Sky Summoner

Whenever you cast an instant or sorcery spell, create a 2/2 blue Drake creature token with flying.

Frantic Search

Draw two cards, then discard two cards. Untap up to three lands.

The Flood of Mars

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
Water Always Wins — Whenever The Flood of Mars attacks, put a flood counter on another target creature or land. If it's a creature, it becomes a copy of The Flood of Mars. If it's a land, it becomes an Island in addition to its other types.

Dream Twist

Target player mills three cards.
Flashback {1}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Eluge, the Shoreless Sea

Eluge's power and toughness are each equal to the number of Islands you control.
Whenever Eluge enters or attacks, put a flood counter on target land. It's an Island in addition to its other types for as long as it has a flood counter on it.
The first instant or sorcery spell you cast each turn costs {U} (or {1}) less to cast for each land you control with a flood counter on it.

Mind Sculpt

Fleet Swallower

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

Resculpt

Exile target artifact or creature. Its controller creates a 4/4 blue and red Elemental creature token.

Patient Rebuilding

At the beginning of your upkeep, target opponent mills three cards, then you draw a card for each land card put into their graveyard this way.

Kairi, the Swirling Sky

Flying, ward {3}
When Kairi, the Swirling Sky dies, choose one —
• Return any number of target nonland permanents with total mana value 6 or less to their owners' hands.
• Mill six cards, then return up to two instant and/or sorcery cards from your graveyard to your hand.

Disturbing Conversion

Flash
Enchant creature
When Disturbing Conversion enters, each player mills two cards.
Enchanted creature gets -X/-0, where X is the number of cards in its controller's graveyard.

Long River's Pull

Gift a card (You may promise an opponent a gift as you cast this spell. If you do, they draw a card before its other effects.)
Counter target creature spell. If the gift was promised, instead counter target spell.

Commander's Sphere

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

Thought Vessel

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

Imperious Mindbreaker

Soulbond (You may pair this creature with another unpaired creature when either enters. They remain paired for as long as you control both of them.)
As long as Imperious Mindbreaker is paired with another creature, each of those creatures has "Whenever this creature attacks, each opponent mills cards equal to its 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

Terisian Mindbreaker

Whenever Terisian Mindbreaker attacks, defending player mills half their library, rounded up.
Unearth {1}{U}{U}{U} ({1}{U}{U}{U}: Return this card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the next end step or if it would leave the battlefield. Unearth only as a sorcery.)

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.)

Wayfarer's Bauble

{2}, {T}, Sacrifice Wayfarer's Bauble: Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Chill of Foreboding

Each player mills five cards.
Flashback {7}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Sol Ring

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.)

Arcane Signet

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

Finale of Revelation

Draw X cards. If X is 10 or more, instead shuffle your graveyard into your library, draw X cards, untap up to five lands, and you have no maximum hand size for the rest of the game.
Exile Finale of Revelation.

Psychic Spiral

Shuffle all cards from your graveyard into your library. Target player mills that many cards.

Wash Out

Return all permanents of the color of your choice to their owners' hands.

Sky Diamond

Into the Story

This spell costs {3} less to cast if an opponent has seven or more cards in their graveyard.
Draw four cards.

Drowner Initiate

Whenever a player casts a blue spell, you may pay {1}. If you do, target player mills two cards.

Jace Beleren

+2: Each player draws a card.
−1: Target player draws a card.
−10: Target player mills twenty cards.

Fraying Sanity

Enchant player
At the beginning of each end step, enchanted player mills X cards, where X is the number of cards put into their graveyard from anywhere this turn.

Flood of Recollection

Return target instant or sorcery card from your graveyard to your hand. Exile Flood of Recollection.

Dreadwaters

Target player mills X cards, where X is the number of lands you control.

Deranged Assistant

{T}, Mill a card: Add {C}. (To mill a card, put the top card of your library into your graveyard.)

Didn't Say Please

Drowned Secrets

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

Jace's Sanctum

Instant and sorcery spells you cast cost {1} less to cast.
Whenever you cast an instant or sorcery spell, scry 1.

Chancellor of the Spires

You may reveal this card from your opening hand. If you do, at the beginning of the first upkeep, each opponent mills seven cards.
Flying
When Chancellor of the Spires enters, you may cast target instant or sorcery card from an opponent's graveyard without paying its mana cost.

Jace's Mindseeker

Flying
When Jace's Mindseeker enters, target opponent mills five cards. You may cast an instant or sorcery spell from among them without paying its mana cost.

Countermand

Counter target spell. Its controller mills four cards.

Drown in Dreams

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