Grimoire Thief

Whenever Grimoire Thief becomes tapped, exile the top three cards of target opponent's library face down.
You may look at cards exiled with Grimoire Thief.
{U}, Sacrifice Grimoire Thief: Turn all cards exiled with Grimoire Thief face up. Counter all spells with those names.

Admiral's Order

Raid — If you attacked this turn, you may pay {U} rather than pay this spell's mana cost.
Counter target spell.

Confounding Riddle

Choose one —
• Look at the top four cards of your library. Put one of them into your hand and the rest into your graveyard.
• Counter target spell unless its controller pays {4}.

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.

Ertai's Trickery

Disruptive Pitmage

{T}: Counter target spell unless its controller pays {1}.
Morph {U} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)

Salvager of Secrets

When Salvager of Secrets enters, return target instant or sorcery card from your graveyard to your hand.

Scatter Ray

Counter target artifact or creature spell unless its controller pays {4}.

Jwari Ruins

Jwari Disruption

Counter target spell unless its controller pays {1}.

Jwari Disruption // Jwari Ruins

River Sneak

River Sneak can't be blocked.
Whenever another Merfolk you control enters, River Sneak gets +1/+1 until end of turn.

Frightful Delusion

Counter target spell unless its controller pays {1}. That player discards a card.

Fervent Denial

Counter target spell.
Flashback {5}{U}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Path of Ancestry

Path of Ancestry enters tapped.
{T}: Add one mana of any color in your commander's color identity. When that mana is spent to cast a creature spell that shares a creature type with your commander, scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Didn't Say Please

Counter target spell. Its controller mills three cards.

Ghost-Lit Warder

{3}{U}, {T}: Counter target spell unless its controller pays {2}.
Channel — {3}{U}, Discard Ghost-Lit Warder: Counter target spell unless its controller pays {4}.

Dissolve

Counter target spell. Scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Declaration of Naught

As Declaration of Naught enters, choose a card name.
{U}: Counter target spell with the chosen name.

Change the Equation

Choose one —
• Counter target spell with mana value 2 or less.
• Counter target red or green spell with mana value 6 or less.

Dream Fracture

Counter target spell. Its controller draws a card.
Draw a card.

Lullmage Mentor

Whenever a spell or ability you control counters a spell, you may create a 1/1 blue Merfolk creature token.
Tap seven untapped Merfolk you control: Counter target spell.

Devious Cover-Up

Counter target spell. If that spell is countered this way, exile it instead of putting it into its owner's graveyard. You may shuffle up to four target cards from your graveyard into your library.

Rites of Refusal

Discard any number of cards. Counter target spell unless its controller pays {3} for each card discarded this way.

Fallowsage

Whenever Fallowsage becomes tapped, you may draw a card.

Cursecatcher

Sacrifice Cursecatcher: Counter target instant or sorcery spell unless its controller pays {1}.

Outwit

Counter target spell that targets a player.

Reliquary Tower

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

Archmage's Charm

Choose one —
• Counter target spell.
• Target player draws two cards.
• Gain control of target nonland permanent with mana value 1 or less.

Quench

Counter target spell unless its controller pays {2}.

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.

Brineborn Cutthroat

Flash (You may cast this spell any time you could cast an instant.)
Whenever you cast a spell during an opponent's turn, put a +1/+1 counter on this creature.

Abstruse Interference

Devoid (This card has no color.)
Counter target spell unless its controller pays {1}. You create a 1/1 colorless Eldrazi Scion creature token. It has "Sacrifice this creature: Add {C}." ({C} represents colorless mana.)

Mana Leak

Counter target spell unless its controller pays {3}.

Hydroblast

Choose one —
• Counter target spell if it's red.
• Destroy target permanent if it's red.

Lay Bare

Counter target spell. Look at its controller's hand.

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.

Lose Focus

Replicate {U} (When you cast this spell, copy it for each time you paid its replicate cost. You may choose new targets for the copies.)
Counter target spell unless its controller pays {2}.

Censor

Counter target spell unless its controller pays {1}.
Cycling {U} ({U}, Discard this card: Draw a card.)

Sky Diamond

Ertai, Wizard Adept

Clash of Wills

Counter target spell unless its controller pays {X}.

Oppressive Will

Counter target spell unless its controller pays {1} for each card in your hand.

Kopala, Warden of Waves

Spells your opponents cast that target a Merfolk you control cost {2} more to cast.
Abilities your opponents activate that target a Merfolk you control cost {2} more to activate.

Wizard Class

(Gain the next level as a sorcery to add its ability.)
You have no maximum hand size.
{2}{U}: Level 2
When this Class becomes level 2, draw two cards.
{4}{U}: Level 3
Whenever you draw a card, put a +1/+1 counter on target creature you control.

Sphinx of the Final Word

This spell can't be countered.
Flying
Hexproof (This creature can't be the target of spells or abilities your opponents control.)
Instant and sorcery spells you control can't be countered.

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.

Myriad Landscape

Myriad Landscape enters tapped.
{T}: Add {C}.
{2}, {T}, Sacrifice Myriad Landscape: Search your library for up to two basic land cards that share a land type, put them onto the battlefield tapped, then shuffle.

Ertai's Scorn

This spell costs {U} less to cast if an opponent cast two or more spells this turn.
Counter target spell.

Prohibit

Kicker {2} (You may pay an additional {2} as you cast this spell.)
Counter target spell if its mana value is 2 or less. If this spell was kicked, counter that spell if its mana value is 4 or less instead.

Lonely Sandbar

Lonely Sandbar enters tapped.
{T}: Add {U}.
Cycling {U} ({U}, Discard this card: Draw a card.)

High Tide

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

Cosi's Trickster

Whenever an opponent shuffles their library, you may put a +1/+1 counter on Cosi's Trickster.

Disruptive Student

{T}: Counter target spell unless its controller pays {1}.

Laquatus's Disdain

Counter target spell cast from a graveyard.
Draw a card.

Clear the Mind

Target player shuffles their graveyard into their library.
Draw a card.

Disruption Protocol

As an additional cost to cast this spell, tap an untapped artifact you control or pay {1}.
Counter target spell.

Kozilek, the Great Distortion

When you cast this spell, if you have fewer than seven cards in hand, draw cards equal to the difference.
Menace
Discard a card with mana value X: Counter target spell with mana value X.

Sol Ring

Lost in the Mist

Counter target spell. Return target permanent to its owner's hand.

Counterspell

Mesmeric Glare

Counter target spell with mana value 3 or less. (Then exile this card. You may cast the creature later from exile.)

Hypnotic Sprite

Hypnotic Sprite // Mesmeric Glare

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.

Thassa's Oracle

When Thassa's Oracle enters, look at the top X cards of your library, where X is your devotion to blue. Put up to one of them on top of your library and the rest on the bottom of your library in a random order. If X is greater than or equal to the number of cards in your library, you win the game. (Each {U} in the mana costs of permanents you control counts toward your devotion to blue.)

Daze

You may return an Island you control to its owner's hand rather than pay this spell's mana cost.
Counter target spell unless its controller pays {1}.

Cancel

Cryptic Command

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

Access Denied

Counter target spell. Create X 1/1 colorless Thopter artifact creature tokens with flying, where X is that spell's mana value.

Island

Make Disappear

Casualty 1 (As you cast this spell, you may sacrifice a creature with power 1 or greater. When you do, copy this spell and you may choose a new target for the copy.)
Counter target spell unless its controller pays {2}.

Mystic Confluence

Choose three. You may choose the same mode more than once.
• Counter target spell unless its controller pays {3}.
• Return target creature to its owner's hand.
• Draw a card.

Omniscience

You may cast spells from your hand without paying their mana costs.

Discombobulate

Counter target spell. Look at the top four cards of your library, then put them back in any order.