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.

Stonybrook Banneret

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
Merfolk spells and Wizard spells you cast cost {1} less to cast.

Gale, Waterdeep Prodigy

Whenever you cast an instant or sorcery spell from your hand, you may cast up to one target card of the other type from your graveyard. If a spell cast from your graveyard this way would be put into your graveyard, exile it instead.
Choose a Background (You can have a Background as a second commander.)

Fierce Guardianship

If you control a commander, you may cast this spell without paying its mana cost.
Counter target noncreature spell.

Spellseeker

When this creature enters, you may search your library for an instant or sorcery card with mana value 2 or less, reveal it, put it into your hand, then shuffle.

Discontinuity

During your turn, this spell costs {2}{U}{U} less to cast.
End the turn. (Exile all spells and abilities from the stack, including this card. The player whose turn it is discards down to their maximum hand size. Damage wears off, and "this turn" and "until end of turn" effects end.)

Galecaster Colossus

Tap an untapped Wizard you control: Return target nonland permanent you don't control to its owner's hand.

Narset, Parter of Veils

Each opponent can't draw more than one card each turn.
−2: Look at the top four cards of your library. You may reveal a noncreature, nonland card from among them and put it into your hand. Put the rest on the bottom of your library in a random order.

Talrand, Sky Summoner

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

Dress Down

Flash
When this enchantment enters, draw a card.
Creatures lose all abilities.
At the beginning of the end step, sacrifice this enchantment.

Quistis Trepe

Blue Magic — When Quistis Trepe enters, you may cast target instant or sorcery card from a graveyard, and mana of any type can be spent to cast that spell. If that spell would be put into a graveyard, exile it instead.

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.

Cyclone Summoner

When this creature enters, if you cast it from your hand, return all permanents to their owners' hands except for Giants, Wizards, and lands.

Rite of Replication

Kicker {5} (You may pay an additional {5} as you cast this spell.)
Create a token that's a copy of target creature. If this spell was kicked, create five of those tokens instead.

Proft's Eidetic Memory

When Proft's Eidetic Memory enters, draw a card.
You have no maximum hand size.
At the beginning of combat on your turn, if you've drawn more than one card this turn, put X +1/+1 counters on target creature you control, where X is the number of cards you've drawn this turn minus one.

Hermes, Overseer of Elpis

Whenever you cast a noncreature spell, create a 1/1 blue Bird creature token with flying and vigilance.
Whenever you attack with one or more Birds, scry 2.

Mystical Tutor

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

Arcane Signet

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

Gogo, Master of Mimicry

{X}{X}, {T}: Copy target activated or triggered ability you control X times. You may choose new targets for the copies. This ability can't be copied and X can't be 0. (Mana abilities can't be targeted.)

Transit Mage

When this creature enters, you may search your library for an artifact card with mana value 4 or 5, reveal it, put it into your hand, then shuffle.

Patron Wizard

Tap an untapped Wizard you control: Counter target spell unless its controller pays {1}.

Minn, Wily Illusionist

Whenever you draw your second card each turn, create a 1/1 blue Illusion creature token with "This token gets +1/+0 for each other Illusion you control."
Whenever an Illusion you control dies, you may put a permanent card with mana value less than or equal to that creature's power from your hand onto the battlefield.

Venser, Shaper Savant

Flash (You may cast this spell any time you could cast an instant.)
When Venser enters, return target spell or permanent to its owner's hand.

Archmage Emeritus

Magecraft — Whenever you cast or copy an instant or sorcery spell, draw a card.

Lightning Greaves

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

Wizard's Retort

This spell costs {1} less to cast if you control a Wizard.
Counter target spell.

Rewind

Counter target spell. Untap up to four lands.

High Tide

Until end of turn, whenever a player taps an Island for mana, that player adds an additional {U}.

Reliquary Tower

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

Minamo, School at Water's Edge

{T}: Add {U}.
{U}, {T}: Untap target legendary permanent.

Riptide Laboratory

{T}: Add {C}.
{1}{U}, {T}: Return target Wizard you control to its owner's hand.

Lulu, Stern Guardian

Whenever an opponent attacks you, choose target creature attacking you. Put a stun counter on that creature.
{3}{U}: Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Azami, Lady of Scrolls

Tap an untapped Wizard you control: Draw a card.

Mindsplice Apparatus

Flash
At the beginning of your upkeep, put an oil counter on this artifact.
Instant and sorcery spells you cast cost {1} less to cast for each oil counter on this artifact.

Spellskite

{U/P}: Change a target of target spell or ability to this creature. ({U/P} can be paid with either {U} or 2 life.)

Shark Typhoon

Whenever you cast a noncreature spell, create an X/X blue Shark creature token with flying, where X is that spell's mana value.
Cycling {X}{1}{U} ({X}{1}{U}, Discard this card: Draw a card.)
When you cycle this card, create an X/X blue Shark creature token with flying.

Sapphire Medallion

Blue spells you cast cost {1} less to cast.

Sensei's Divining Top

{1}: Look at the top three cards of your library, then put them back in any order.
{T}: Draw a card, then put this artifact on top of its owner's library.

Rhystic Study

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

Flare of Denial

You may sacrifice a nontoken blue creature rather than pay this spell's mana cost.
Counter target spell.

Cryptic Command

Choose two —
• Counter target spell.
• Return target permanent to its owner's hand.
• Tap all creatures your opponents control.
• Draw a card.

Coat of Arms

Each creature gets +1/+1 for each other creature on the battlefield that shares at least one creature type with it. (For example, if two Goblin Warriors and a Goblin Shaman are on the battlefield, each gets +2/+2.)

Swan Song

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

Arcanis the Omnipotent

{T}: Draw three cards.
{2}{U}{U}: Return Arcanis to its owner's hand.

Illusion

This creature gets +1/+0 for each other Illusion you control.

Ponder

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

Baral's Expertise

Return up to three target artifacts and/or creatures to their owners' hands.
You may cast a spell with mana value 4 or less from your hand without paying its mana cost.

Soldevi Excavations

If this land would enter, sacrifice an untapped Island instead. If you do, put this land onto the battlefield. If you don't, put it into its owner's graveyard.
{T}: Add {C}{U}.
{1}, {T}: Scry 1.

Naban, Dean of Iteration

If a Wizard you control entering causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.

Shark

Disallow

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

Day's Undoing

Each player shuffles their hand and graveyard into their library, then draws seven cards. If it's your turn, end the turn. (Exile all spells and abilities from the stack, including this card. Discard down to your maximum hand size. Damage wears off, and "this turn" and "until end of turn" effects end.)

Snapcaster Mage

Flash
When this creature enters, target instant or sorcery card in your graveyard gains flashback until end of turn. The flashback cost is equal to its mana cost. (You may cast that card from your graveyard for its flashback cost. Then exile it.)

Drake

Island

Brainstorm

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

Portal Mage

Flash
When this creature enters during the declare attackers step, you may reselect which player or permanent target attacking creature is attacking. (It can't attack its controller or their permanents.)

Alphinaud Leveilleur

Partner with Alisaie Leveilleur (When this creature enters, target player may put Alisaie Leveilleur into their hand from their library, then shuffle.)
Vigilance
Eukrasia — Whenever you cast your second spell each turn, draw a card.

Thassa, Deep-Dwelling

Indestructible
As long as your devotion to blue is less than five, Thassa isn't a creature.
At the beginning of your end step, exile up to one other target creature you control, then return that card to the battlefield under your control.
{3}{U}: Tap another target creature.

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.

Narset's Reversal

Copy target instant or sorcery spell, then return it to its owner's hand. You may choose new targets for the copy.

Aether Channeler

When this creature enters, choose one —
• Create a 1/1 white Bird creature token with flying.
• Return another target nonland permanent to its owner's hand.
• Draw a card.

Gadwick, the Wizened

When Gadwick enters, draw X cards.
Whenever you cast a blue spell, tap target nonland permanent an opponent controls.

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.")

Expropriate

Council's dilemma — Starting with you, each player votes for time or money. For each time vote, take an extra turn after this one. For each money vote, choose a permanent owned by the voter and gain control of it. Exile Expropriate.

Back to Basics

Nonbasic lands don't untap during their controllers' untap steps.

Sol Ring

River's Rebuke

Return all nonland permanents target player controls to their owner's hand.

Castle Vantress

This land enters tapped unless you control an Island.
{T}: Add {U}.
{2}{U}{U}, {T}: Scry 2.

Fatespinner

At the beginning of each opponent's upkeep, that player chooses draw step, main phase, or combat phase. The player skips each instance of the chosen step or phase this turn.

Midnight Clock

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

Teferi, Mage of Zhalfir

Flash
Creature cards you own that aren't on the battlefield have flash.
Each opponent can cast spells only any time they could cast 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.)

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.

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.