Lost in Thought

Enchant creature
Enchanted creature can't attack or block, and its activated abilities can't be activated. Its controller may exile three cards from their graveyard for that player to ignore this effect until end of turn.

Circular Logic

Counter target spell unless its controller pays {1} for each card in your graveyard.
Madness {U} (If you discard this card, discard it into exile. When you do, cast it for its madness cost or put it into your graveyard.)

Elite Instructor

When this creature enters, draw a card, then discard a card.

Refute

Counter target spell. Draw a card, then discard a card.

Stoic Champion

Whenever a player cycles a card, this creature gets +2/+2 until end of turn.

Thought Courier

Terramorphic Expanse

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

Confound

Counter target spell that targets a creature.
Draw a card.

Prairie Stream

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

Mental Journey

Draw three cards.
Basic landcycling {1}{U} ({1}{U}, Discard this card: Search your library for a basic land card, reveal it, put it into your hand, then shuffle.)

Jace, Architect of Thought

+1: Until your next turn, whenever a creature an opponent controls attacks, it gets -1/-0 until end of turn.
−2: Reveal the top three cards of your library. An opponent separates those cards into two piles. Put one pile into your hand and the other on the bottom of your library in any order.
−8: For each player, search that player's library for a nonland card and exile it, then that player shuffles. You may cast those cards without paying their mana costs.

Reliquary Tower

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

Deduce

Draw a card. Investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this token: Draw a card.")

Thought Collapse

Counter target spell. Its controller mills three cards.

Port Town

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

Consider

Surveil 1. (Look at the top card of your library. You may put it into your graveyard.)
Draw a card.

Sokrates, Athenian Teacher

Defender
Sokrates has hexproof as long as it's untapped.
Sokratic Dialogue — {T}: Until end of turn, target creature gains "If this creature would deal combat damage to a player, prevent that damage. This creature's controller and that player each draw half that many cards, rounded down."

Brainstorm

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

Rogue's Passage

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

Exotic Orchard

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

Contradict

Duelist of the Mind

Flying, vigilance
Duelist of the Mind's power is equal to the number of cards you've drawn this turn.
Whenever you commit a crime, you may draw a card. If you do, discard a card. This ability triggers only once each turn.

Pondering Mage

When this creature enters, look at the top three cards of your library, then put them back in any order. You may shuffle. Draw a card.

Body of Knowledge

Body of Knowledge's power and toughness are each equal to the number of cards in your hand.
You have no maximum hand size.
Whenever this creature is dealt damage, draw that many cards.

Thoughtbound Phantasm

Defender
Whenever you surveil, put a +1/+1 counter on this creature.
As long as this creature has three or more +1/+1 counters on it, it can attack as though it didn't have defender.

Command Tower

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

Thoughtbind

Counter target spell with mana value 4 or less.

Deliberate

Train of Thought

Replicate {1}{U} (When you cast this spell, copy it for each time you paid its replicate cost.)
Draw a card.

Taunt

During target player's next turn, creatures that player controls attack you if able.

Temple of Enlightenment

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 {W} or {U}.

Tranquil Cove

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

Anticipate

Look at the top three cards of your library. Put one of them into your hand and the rest on the bottom of your library in any order.

Cunning

Enchant creature
Enchanted creature gets +3/+3.
When enchanted creature attacks or blocks, sacrifice this Aura at the beginning of the next cleanup step.

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.)

Trial of Knowledge

When this enchantment enters, draw three cards, then discard a card.
When a Cartouche you control enters, return this enchantment to its owner's hand.

Thoughtweft Gambit

Tap all creatures your opponents control and untap all creatures you control.

Thinking Cap

Equipped creature gets +1/+2.
Equip Detective {1}
Equip {3} ({3}: Attach to target creature you control. Equip only as a sorcery.)

Concentrate

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.

Words of Wind

{1}: The next time you would draw a card this turn, each player returns a permanent they control to its owner's hand instead.

Think Twice

Draw a card.
Flashback {2}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Thought Scour

Target player mills two cards.
Draw a card.

Wonder

Flying
As long as this card is in your graveyard and you control an Island, creatures you control have flying.

Rethink

Counter target spell unless its controller pays {X}, where X is its mana value.

Convolute

Counter target spell unless its controller pays {4}.

Grell Philosopher

Aberrant Tinkering — When this creature enters and at the beginning of your upkeep, each Horror you control gains all activated abilities of target artifact an opponent controls until end of turn. You may spend blue mana as though it were mana of any color to activate those abilities.

Exchange of Words

When this enchantment enters, choose two target creatures. For as long as this enchantment remains on the battlefield, exchange the text boxes of those creatures.

Thought Vessel

Brain in a Jar

{1}, {T}: Put a charge counter on this artifact, then you may cast an instant or sorcery spell with mana value equal to the number of charge counters on this artifact from your hand without paying its mana cost.
{3}, {T}, Remove X charge counters from this artifact: Scry X.

Hubris

Return target creature and all Auras attached to it to their owners' hands.

Mind Stone

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

Stoic Sphinx

Flash
Flying
This creature has hexproof as long as you haven't cast a spell this turn.

Think Tank

At the beginning of your upkeep, surveil 1. (Look at the top card of your library. You may put that card into your graveyard.)

Mystic Sanctuary

({T}: Add {U}.)
This land enters tapped unless you control three or more other Islands.
When this land enters untapped, you may put target instant or sorcery card from your graveyard on top of your library.

Ponder

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

Nephalia Academy

If a spell or ability an opponent controls causes you to discard a card, you may reveal that card and put it on top of your library instead of putting it anywhere else.
{T}: Add {C}.

Staggering Insight

Enchant creature
Enchanted creature gets +1/+1 and has lifelink and "Whenever this creature deals combat damage to a player, draw a card."

Thought Harvester

Devoid (This card has no color.)
Flying
Whenever you cast a colorless spell, target opponent exiles the top card of their library.

Traveling Philosopher

Scholar of New Horizons

This creature enters with a +1/+1 counter on it.
{T}, Remove a counter from a permanent you control: Search your library for a Plains card and reveal it. If an opponent controls more lands than you, you may put that card onto the battlefield tapped. If you don't put the card onto the battlefield, put it into your hand. Then shuffle.

Island

Voice of Reason

Bewilder

Target creature gets -3/-0 until end of turn.
Draw a card.

Forget

Target player discards two cards, then draws as many cards as they discarded this way.

Evolving Wilds

Sage's Knowledge

Return target sorcery card from your graveyard to your hand.

Plains

Persuasion

Enchant creature (Target a creature as you cast this. This card enters attached to that creature.)
You control enchanted creature.

Demystify

Brainwash

Enchant creature
Enchanted creature can't attack unless its controller pays {3}.

Outwit

Counter target spell that targets a player.

Mnemonic Wall

Defender
When this creature enters, you may return target instant or sorcery card from your graveyard to your hand.

Stoic Farmer

When this creature enters, search your library for a basic Plains card and reveal it. If an opponent controls more lands than you, put it onto the battlefield tapped. Otherwise, put it into your hand. Then shuffle.
Foretell {1}{W} (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.)

Sphere of Reason

If a blue source would deal damage to you, prevent 2 of that damage.

Last Thoughts

Draw a card.
Cipher (Then you may exile this spell card encoded on a creature you control. Whenever that creature deals combat damage to a player, its controller may cast a copy of the encoded card without paying its mana cost.)

Curiosity

Enchant creature
Whenever enchanted creature deals damage to an opponent, you may draw a card.

Controvert

Counter target spell.
Recover {2}{U}{U} (When a creature is put into your graveyard from the battlefield, you may pay {2}{U}{U}. If you do, return this card from your graveyard to your hand. Otherwise, exile this card.)

Wall of Lost Thoughts

Defender (This creature can't attack.)
When this creature enters, target player mills four cards. (They put the top four cards of their library into their graveyard.)

Thought Sponge

Flash
This creature enters with a number of +1/+1 counters on it equal to the greatest number of cards an opponent has drawn this turn.
When this creature dies, draw cards equal to its power.