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.

Overwhelming Intellect

Counter target creature spell. Draw cards 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 Brineborn Cutthroat.

Merfolk

Access Denied

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

Kira, Great Glass-Spinner

Flying
Creatures you control have "Whenever this creature becomes the target of a spell or ability for the first time each turn, counter that spell or ability."

Lier, Disciple of the Drowned

Spells can't be countered.
Each instant and sorcery card in your graveyard has flashback. The flashback cost is equal to that card's mana cost.

Clutch of Currents

Return target creature to its owner's hand.
Awaken 3—{4}{U} (If you cast this spell for {4}{U}, also put three +1/+1 counters on target land you control and it becomes a 0/0 Elemental creature with haste. It's still a land.)

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.

Negate

Hornswoggle

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

Echo Mage

Level up {1}{U} ({1}{U}: Put a level counter on this. Level up only as a sorcery.)
LEVEL 2-3
2/4
{U}{U}, {T}: Copy target instant or sorcery spell. You may choose new targets for the copy.
LEVEL 4+
2/5
{U}{U}, {T}: Copy target instant or sorcery spell twice. You may choose new targets for the copies.

Syphon Essence

Counter target creature or planeswalker spell. Create a Blood token. (It's an artifact with "{1}, {T}, Discard a card, Sacrifice this artifact: Draw a card.")

Diamond Knight

Vigilance (Attacking doesn't cause this creature to tap.)
As Diamond Knight enters the battlefield, choose a color.
Whenever you cast a spell of the chosen color, put a +1/+1 counter on Diamond Knight.

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.

Out of Air

This spell costs {2} less to cast if it targets a creature spell.
Counter target spell.

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.)

Geist Snatch

Counter target creature spell. Create a 1/1 blue Spirit creature token with flying.

Disappearing Act

As an additional cost to cast this spell, return a permanent you control to its owner's hand.
Counter target spell.

Didn't Say Please

Counter target spell. Its controller mills three cards.

Lost in the Mist

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

Tolarian Terror

This spell costs {1} less to cast for each instant and sorcery card in your graveyard.
Ward {2} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {2}.)

Artistic Refusal

Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for {1} or one mana of that creature's color.)
Choose one or both —
• Counter target spell.
• Draw two cards, then discard a card.

Contradict

Annul

Counter target artifact or enchantment spell.

Cryptic Serpent

This spell costs {1} less to cast for each instant and sorcery card in your graveyard.

An Offer You Can't Refuse

Counter target noncreature spell. Its controller creates two Treasure tokens. (They're artifacts with "{T}, Sacrifice this artifact: Add one mana of any color.")

Fuel for the Cause

Counter target spell, then proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Flux Channeler

Whenever you cast a noncreature spell, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Broken Concentration

Counter target spell.
Madness {3}{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.)

Essence Capture

Counter target creature spell. Put a +1/+1 counter on up to one target creature you control.

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.

Force Spike

Counter target spell unless its controller pays {1}.

Dissolve

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

Failed Inspection

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

Trawler Drake

Flying
Trawler Drake enters the battlefield with an oil counter on it.
Trawler Drake gets +1/+1 for each oil counter on it.
Whenever you cast a noncreature spell, put an oil counter on Trawler Drake.

Anticognition

Counter target creature or planeswalker spell unless its controller pays {2}. If an opponent has eight or more cards in their graveyard, instead counter that spell, then scry 2.

Countermand

Counter target spell. Its controller mills four cards.

Blood

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

Voracious Greatshark

Flash
When Voracious Greatshark enters the battlefield, counter target artifact or creature spell.

Launch Mishap

Counter target creature or planeswalker spell. Create a 1/1 colorless Thopter artifact creature token with flying.

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.

Dismal Failure

Counter target spell. Its controller discards a card.

Deny Existence

Counter target creature spell. If that spell is countered this way, exile it instead of putting it into its owner's graveyard.

Last Word

This spell can't be countered.
Counter target spell.

Desertion

Counter target spell. If an artifact or creature spell is countered this way, put that card onto the battlefield under your control instead of into its owner's graveyard.

Neutralizing Blast

Thopter

Island

Deprive

As an additional cost to cast this spell, return a land you control to its owner's hand.
Counter target spell.

Deny the Divine

Counter target creature or enchantment spell. If that spell is countered this way, exile it instead of putting it into its owner's graveyard.

Counterspell

Dismiss

Sphinx of the Final Word

This spell can't be countered.
Flying, hexproof
Instant and sorcery spells you control can't be countered.

Overwhelming Denial

Surge {U}{U} (You may cast this spell for its surge cost if you or a teammate has cast another spell this turn.)
This spell can't be countered.
Counter target spell.

Bone to Ash

Counter target creature spell.
Draw a card.

Mindstatic

Counter target spell unless its controller pays {6}.

Ertai's Scorn

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

Outwit

Counter target spell that targets a player.

Treasure

{T}, Sacrifice this artifact: Add one mana of any color.

Exclude

Nezahal, Primal Tide

This spell can't be countered.
You have no maximum hand size.
Whenever an opponent casts a noncreature spell, draw a card.
Discard three cards: Exile Nezahal, Primal Tide. Return it to the battlefield tapped under its owner's control at the beginning of the next end step.

Essence Scatter

Kefnet's Last Word

Gain control of target artifact, creature, or enchantment. Lands you control don't untap during your next untap step.

Fierce Guardianship

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

Cancel

Dispel

Mystical Tutor

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

Lay Bare

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

Draining Whelk

Flash
Flying
When Draining Whelk enters the battlefield, counter target spell. Put X +1/+1 counters on Draining Whelk, where X is that spell's mana value.

Hinder

Counter target spell. If that spell is countered this way, put that card on the top or bottom of its owner's library instead of into that player's graveyard.

Saw It Coming

Counter target spell.
Foretell {1}{U} (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.)

Cryptic Command

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

Disdainful Stroke

Counter target spell with mana value 4 or greater.

Disallow

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