Have

Reliquary Tower

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

Negate

Cryptic Command

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

Spellseeker

When Spellseeker enters the battlefield, 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.

Tribute Mage

When Tribute Mage enters the battlefield, you may search your library for an artifact card with mana value 2, reveal that card, put it into your hand, then shuffle.

Sapphire Medallion

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

Archaeomancer

When Archaeomancer enters the battlefield, return target instant or sorcery card from your graveyard to your hand.

Don't Have

Rhystic Study

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

Arcane Signet

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

Vedalken Shackles

You may choose not to untap Vedalken Shackles during your untap step.
{2}, {T}: Gain control of target creature with power less than or equal to the number of Islands you control for as long as Vedalken Shackles remains tapped.

Dramatic Reversal

Untap all nonland permanents you control.

Wavebreak Hippocamp

Whenever you cast your first spell during each opponent's turn, draw a card.

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.

Snapcaster Mage

Flash
When Snapcaster Mage enters the battlefield, 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.)

Ponder

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

Archmage Emeritus

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

Hullbreacher

Flash
If an opponent would draw a card except the first one they draw in each of their draw steps, instead you create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Seat of the Synod

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.

Swan Song

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

Blue Sun's Zenith

Target player draws X cards. Shuffle Blue Sun's Zenith into its owner's library.

Guile

Guile can't be blocked except by three or more creatures.
If a spell or ability you control would counter a spell, instead exile that spell and you may play that card without paying its mana cost.
When Guile is put into a graveyard from anywhere, shuffle it into its owner's library.

Mystic Sanctuary

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

Fierce Guardianship

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

Disdainful Stroke

Counter target spell with mana value 4 or greater.

Unwind

Counter target noncreature spell. Untap up to three lands.

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.)

Palinchron

Flying
When Palinchron enters the battlefield, untap up to seven lands.
{2}{U}{U}: Return Palinchron to its owner's hand.

Insidious Will

Choose one —
• Counter target spell.
• You may choose new targets for target spell.
• Copy target instant or sorcery spell. You may choose new targets for the copy.

Rewind

Counter target spell. Untap up to four lands.

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.)

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.")

Disallow

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

Chain of Vapor

Return target nonland permanent to its owner's hand. Then that permanent's controller may sacrifice a land. If the player does, they may copy this spell and may choose a new target for that copy.

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.

Capsize

Buyback {3} (You may pay an additional {3} as you cast this spell. If you do, put this card into your hand as it resolves.)
Return target permanent to its owner's hand.

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.

Dispel

Sol Ring

Mental Misstep

({U/P} can be paid with either {U} or 2 life.)
Counter target spell with mana value 1.

Fact or Fiction

Reveal the top five cards of your library. An opponent separates those cards into two piles. Put one pile into your hand and the other into your graveyard.

Talrand, Sky Summoner

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

Arcane Denial

Counter target spell. Its controller may draw up to two cards at the beginning of the next turn's upkeep.
You draw a card at the beginning of the next turn's upkeep.

Counterspell

High Tide

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

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.

Isochron Scepter

Imprint — When Isochron Scepter enters the battlefield, you may exile an instant card with mana value 2 or less from your hand.
{2}, {T}: You may copy the exiled card. If you do, you may cast the copy without paying its mana cost.

Mana Leak

Counter target spell unless its controller pays {3}.