Overwhelming Intellect

Counter target creature spell. Draw cards equal to that spell's mana value.

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.)

Annul

Counter target artifact or enchantment spell.

Confound

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

Out of Bounds

Assist (Another player can pay up to {3} of this spell's cost.)
Counter target spell.

Defabricate

Choose one —
• Counter target artifact or enchantment spell. If a spell is countered this way, exile it instead of putting it into its owner's graveyard.
• Counter target activated or triggered ability.

Voidmage Husher

Flash (You may cast this spell any time you could cast an instant.)
When this creature enters, counter target activated ability. (Mana abilities can't be targeted.)
Whenever you cast a spell, you may return this creature to its owner's hand.

Thassa's Intervention

Choose one —
• Look at the top X cards of your library. Put up to two of them into your hand and the rest on the bottom of your library in a random order.
• Counter target spell unless its controller pays twice {X}.

Dissolve

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

Mirrorshell Crab

Ward {3} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {3}.)
Channel — {2}{U}, Discard this card: Counter target spell or ability unless its controller pays {3}.

Aetherize

Return all attacking creatures to their owner's hand.

Discombobulate

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

Counterspell

Sword Coast Sailor

Commander creatures you own have "Whenever this creature attacks a player, if no opponent has more life than that player, this creature can't be blocked this turn."

Flow of Knowledge

Draw a card for each Island you control, then discard two cards.

Stratus Dancer

Flying
Megamorph {1}{U} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its megamorph cost and put a +1/+1 counter on it.)
When this creature is turned face up, counter target instant or sorcery spell.

Run Away Together

Choose two target creatures controlled by different players. Return those creatures to their owners' hands.

Keep Safe

Counter target spell that targets a permanent you control.
Draw a card.

Sol Ring

Essence Scatter

Draining Whelk

Flash
Flying
When this creature enters, counter target spell. Put X +1/+1 counters on this creature, where X is that spell's mana value.

Condescend

Counter target spell unless its controller pays {X}. 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.)

Rewind

Counter target spell. Untap up to four lands.

Sister of Silence

Flash
Psychic Abomination — When this creature enters, counter target instant spell, sorcery spell, activated ability, or triggered ability.

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.)

Island

Brine Seer

{2}{U}, {T}: Reveal any number of blue cards in your hand. Counter target spell unless its controller pays {1} for each card revealed this way.

Wonder

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

Whelming Wave

Return all creatures to their owners' hands except for Krakens, Leviathans, Octopuses, and Serpents.

Clash of Wills

Counter target spell unless its controller pays {X}.

Bane's Contingency

Counter target spell. If that spell targets a commander you control, instead counter that spell, scry 2, then draw a card.

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.

Voidmage Apprentice

Morph {2}{U}{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.)
When this creature is turned face up, counter target spell.

Scourge of Fleets

When this creature enters, return each creature your opponents control with toughness X or less to its owner's hand, where X is the number of Islands you control.

Sinister Sabotage

Counter target spell.
Surveil 1. (Look at the top card of your library. You may put it into your graveyard.)

Voracious Greatshark

Flash (You may cast this spell any time you could cast an instant.)
When this creature enters, counter target artifact or creature spell.

Disdainful Stroke

Counter target spell with mana value 4 or greater.

Tidal Control

Cumulative upkeep {2} (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.)
Pay 2 life or {2}: Counter target red or green spell. Any player may activate this ability.

Syncopate

Counter target spell unless its controller pays {X}. If that spell is countered this way, exile it instead of putting it into its owner's graveyard.

Logic Knot

Delve (Each card you exile from your graveyard while casting this spell pays for {1}.)
Counter target spell unless its controller pays {X}.

Artful Dodge

Target creature can't be blocked this turn.
Flashback {U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Siren Stormtamer

Flying
{U}, Sacrifice this creature: Counter target spell or ability that targets you or a creature you control.

Negate

Supreme Will

Choose one —
• Counter target spell unless its controller pays {3}.
• Look at the top four cards of your library. Put one of them into your hand and the rest on the bottom of your library in any order.

Spell Crumple

Counter target spell. If that spell is countered this way, put it on the bottom of its owner's library instead of into that player's graveyard. Put Spell Crumple on the bottom of its owner's library.

Nullify

Dispel

Wash Away

Cleave {1}{U}{U} (You may cast this spell for its cleave cost. If you do, remove the words in square brackets.)
Counter target spell [that wasn't cast from its owner's hand].

Cancel

Declaration of Naught

As this enchantment enters, choose a card name.
{U}: Counter target spell with the chosen name.

Charix, the Raging Isle

Spells your opponents cast that target Charix cost {2} more to cast.
{3}: Charix gets +X/-X until end of turn, where X is the number of Islands you control.

Hornswoggle

Counter target creature spell. You create a Treasure token. (It's an artifact with "{T}, Sacrifice this token: Add one mana of any color.")

Kheru Spellsnatcher

Morph {4}{U}{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.)
When this creature is turned face up, counter target spell. If that spell is countered this way, exile it instead of putting it into its owner's graveyard. You may cast that card without paying its mana cost for as long as it remains exiled.

Campfire

{1}, {T}: You gain 2 life.
{2}, {T}, Exile this artifact: Put all commanders you own from the command zone and from your graveyard into your hand. Then shuffle your graveyard into your library.

Consuming Tide

Each player chooses a nonland permanent they control. Return all nonland permanents not chosen this way to their owners' hands. Then you draw a card for each opponent who has more cards in their hand than you.

Neutralize

Counter target spell.
Cycling {2} ({2}, Discard this card: Draw a card.)

Engulf the Shore

Return to their owners' hands all creatures with toughness less than or equal to the number of Islands you control.

Lay Bare

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

Unwind

Counter target noncreature spell. Untap up to three lands.

Flow of Ideas

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.

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.

Burnished Hart

{3}, Sacrifice this creature: Search your library for up to two basic land cards, put them onto the battlefield tapped, then shuffle.