Solve the Equation

Search your library for an instant or sorcery card, reveal it, put it into your hand, then shuffle.

Disallow

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

Force of Will

You may pay 1 life and exile a blue card from your hand rather than pay this spell's mana cost.
Counter target spell.

Sphinx's Tutelage

Whenever you draw a card, target opponent mills two cards. If two nonland cards that share a color were milled this way, repeat this process.
{5}{U}: Draw a card, then discard a card.

Cyclonic Rift

Return target nonland permanent you don't control to its owner's hand.
Overload {6}{U} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Thought Scour

Target player mills two cards.
Draw a card.

Grindstone

{3}, {T}: Target player mills two cards. If two cards that share a color were milled this way, repeat this process.

Ponder

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

Trickbind

Split second (As long as this spell is on the stack, players can't cast spells or activate abilities that aren't mana abilities.)
Counter target activated or triggered ability. If a permanent's ability is countered this way, activated abilities of that permanent can't be activated this turn. (Mana abilities can't be targeted.)

Memory Erosion

Whenever an opponent casts a spell, that player mills two cards.

Counterspell

Mystic Remora

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}.

Traumatize

Target player mills half their library, rounded down.

Tasha's Hideous Laughter

Each opponent exiles cards from the top of their library until that player has exiled cards with total mana value 20 or more.

Hedron Crab

Landfall — Whenever a land you control enters, target player mills three cards.

Mystical Tutor

Search your library for an instant or sorcery card, reveal it, then shuffle and put that card on top.

Sphinx Mindbreaker

Flying
When Sphinx Mindbreaker enters, 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.

Maddening Cacophony

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

Mana Drain

Counter target spell. At the beginning of your next main phase, add an amount of {C} equal to that spell's mana value.

Mesmeric Orb

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

Extract

Search target player's library for a card and exile it. Then that player shuffles.

Baral, Chief of Compliance

Instant and sorcery spells you cast cost {1} less to cast.
Whenever a spell or ability you control counters a spell, you may draw a card. If you do, discard a card.

Jester's Cap

{2}, {T}, Sacrifice Jester's Cap: Search target player's library for three cards and exile them. Then that player shuffles.

Transmute Artifact

Sacrifice an artifact. If you do, search your library for an artifact card. If that card's mana value is less than or equal to the sacrificed artifact's mana value, put it onto the battlefield. If it's greater, you may pay {X}, where X is the difference. If you do, put it onto the battlefield. If you don't, put it into its owner's graveyard. Then shuffle.

Drowned Secrets

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

Preordain

Scry 2, then draw a card. (To scry 2, look at the top two cards of your library, then put any number of them on the bottom and the rest on top in any order.)

Fabricate

Search your library for an artifact card, reveal it, put it into your hand, then shuffle.

Long-Term Plans

Search your library for a card, then shuffle and put that card third from the top.

Negate

Rhystic Study

Whenever an opponent casts a spell, you may draw a card unless that player pays {1}.

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.

Ruin Crab

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

Brainstorm

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

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.)

Pact of Negation

Counter target spell.
At the beginning of your next upkeep, pay {3}{U}{U}. If you don't, you lose the game.

Stifle

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

Snow-Covered Island

Visions of Beyond

Draw a card. If a graveyard has twenty or more cards in it, draw three cards instead.

Swan Song

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

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.)

Venture Deeper

Target player mills four cards. (Then exile this card. You may cast the creature later from exile.)

Merfolk Secretkeeper

Merfolk Secretkeeper // Venture Deeper

Psychic Corrosion

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

Force of Negation

If it's not your turn, you may exile a blue card from your hand rather than pay this spell's mana cost.
Counter target noncreature spell. If that spell is countered this way, exile it instead of putting it into its owner's graveyard.

Tale's End

Counter target activated ability, triggered ability, or legendary spell.

Flusterstorm

Counter target instant or sorcery spell unless its controller pays {1}.
Storm (When you cast this spell, copy it for each spell cast before it this turn. You may choose new targets for the copies.)