Glen Elendra Guardian

Flash
Flying
This creature enters with a -1/-1 counter on it.
{1}{U}, Remove a counter from this creature: Counter target noncreature spell. Its controller draws a card.

Invasive Surgery

Counter target sorcery spell.
Delirium — If there are four or more card types among cards in your graveyard, search the graveyard, hand, and library of that spell's controller for any number of cards with the same name as that spell, exile those cards, then that player shuffles.

Sunken Field

Enchant land
Enchanted land has "{T}: Counter target spell unless its controller pays {1}."

Sister of Silence

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

Diplomatic Escort

{U}, {T}, Discard a card: Counter target spell or ability that targets a creature.

Mana Tithe

Counter target spell unless its controller pays {1}.

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.

Ayesha Tanaka

Banding (Any creatures with banding, and up to one without, can attack in a band. Bands are blocked as a group. If any creatures with banding you control are blocking or being blocked by a creature, you divide that creature's combat damage, not its controller, among any of the creatures it's being blocked by or is blocking.)
{T}: Counter target activated ability from an artifact source unless that ability's controller pays {W}. (Mana abilities can't be targeted.)

Blue Elemental Blast

Choose one —
• Counter target red spell.
• Destroy target red permanent.

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.

Intervene

Counter target spell that targets a creature.

Azorius Guildmage

{2}{W}: Tap target creature.
{2}{U}: Counter target activated ability. (Mana abilities can't be targeted.)

Mindreaver

Heroic — Whenever you cast a spell that targets this creature, exile the top three cards of target player's library.
{U}{U}, Sacrifice this creature: Counter target spell with the same name as a card exiled with this creature.

Martyr of Frost

{2}, Reveal X blue cards from your hand, Sacrifice this creature: Counter target spell unless its controller pays {X}.

Douse

Saruman's Trickery

Counter target spell.
Amass Orcs 1. (Put a +1/+1 counter on an Army you control. It's also an Orc. If you don't control an Army, create a 0/0 black Orc Army creature token first.)

Scatter to the Winds

Counter target spell.
Awaken 3—{4}{U}{U} (If you cast this spell for {4}{U}{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.)

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.

Spiketail Drake

Flying
Sacrifice this creature: Counter target spell unless its controller pays {3}.

Ghost-Lit Warder

{3}{U}, {T}: Counter target spell unless its controller pays {2}.
Channel — {3}{U}, Discard this card: Counter target spell unless its controller pays {4}.

Hope-Ender Coatl

Devoid (This card has no color.)
Flash
When you cast this spell, counter target spell an opponent controls unless they pay {1}.
Flying

Declaration of Naught

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

Overcharged Amalgam

Flash
Flying
Exploit (When this creature enters, you may sacrifice a creature.)
When this creature exploits a creature, counter target spell, activated ability, or triggered ability.

Plains

Hisoka, Minamo Sensei

{2}{U}, Discard a card: Counter target spell if it has the same mana value as the discarded card.

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.

Louisoix's Sacrifice

As an additional cost to cast this spell, sacrifice a legendary creature or pay {2}.
Counter target activated ability, triggered ability, or noncreature spell.

Ertai, the Corrupted

{U}, {T}, Sacrifice a creature or enchantment: Counter target spell.

Spiketail Drakeling

Flying
Sacrifice this creature: Counter target spell unless its controller pays {2}.

Spider-Sense

Web-slinging {U} (You may cast this spell for {U} if you also return a tapped creature you control to its owner's hand.)
Counter target instant spell, sorcery spell, or triggered ability.

Daring Apprentice

{T}, Sacrifice this creature: Counter target spell.

Unyaro Griffin

Flying
Sacrifice this creature: Counter target red instant or sorcery spell.

Counterspell

Cerulean Drake

Flying
Protection from red (This creature can't be blocked, targeted, dealt damage, enchanted, or equipped by anything red.)
Sacrifice this creature: Counter target spell that targets you.

Cursecatcher

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

Dispel

Swamp

Deathgrip

Disciple of the Ring

{1}, Exile an instant or sorcery card from your graveyard: Choose one —
• Counter target noncreature spell unless its controller pays {2}.
• This creature gets +1/+1 until end of turn.
• Tap target creature.
• Untap target creature.

Rewind

Counter target spell. Untap up to four lands.

Spell Swindle

Counter target spell. Create X Treasure tokens, where X is that spell's mana value. (They're artifacts with "{T}, Sacrifice this token: Add one mana of any color.")

Silumgar Sorcerer

Flash (You may cast this spell any time you could cast an instant.)
Flying
Exploit (When this creature enters, you may sacrifice a creature.)
When this creature exploits a creature, counter target creature spell.

Vodalian Mage

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

Mage's Attendant

When this creature enters, create a 1/1 blue Wizard creature token with "{1}, Sacrifice this token: Counter target noncreature spell unless its controller pays {1}."

Transcendent Dragon

Flash
Flying
When this creature enters, if you cast it, counter target spell. If that spell is countered this way, exile it instead of putting it into its owner's graveyard, then you may cast it without paying its mana cost.

Nimble Obstructionist

Flash
Flying
Cycling {2}{U} ({2}{U}, Discard this card: Draw a card.)
When you cycle this card, counter target activated or triggered ability you don't control.

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

Phantom Interference

Spree (Choose one or more additional costs.)
+ {3} — Create a 2/2 white Spirit creature token with flying.
+ {1} — Counter target spell unless its controller pays {2}.

Concerted Defense

Counter target noncreature spell unless its controller pays {1} plus an additional {1} for each creature in your party. (Your party consists of up to one each of Cleric, Rogue, Warrior, and Wizard.)

Mausoleum Wanderer

Flying
Whenever another Spirit you control enters, this creature gets +1/+1 until end of turn.
Sacrifice this creature: Counter target instant or sorcery spell unless its controller pays {X}, where X is this creature's power.

Fear of Impostors

Flash
When this creature enters, counter target spell. Its controller manifests dread. (That player looks at the top two cards of their library, then puts one onto the battlefield face down as a 2/2 creature and the other into their graveyard. If it's a creature card, it can be turned face up any time for its mana cost.)

Spiketail Hatchling

Flying (This creature can't be blocked except by creatures with flying or reach.)
Sacrifice this creature: Counter target spell unless its controller pays {1}.

Glorious Gale

Counter target creature spell. If it was a legendary spell, the Ring tempts you.

Disruptive Student

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

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.

Siren Stormtamer

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

Adric, Mathematical Genius

{2}{U}, {T}: Copy target activated or triggered ability you control. You may choose new targets for the copy.
Ultimate Sacrifice — {1}{U}, Sacrifice Adric: Counter target activated or triggered ability.
Doctor's companion (You can have two commanders if the other is the Doctor.)

Silumgar Spell-Eater

Megamorph {4}{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 spell unless its controller pays {3}.

Abjure

As an additional cost to cast this spell, sacrifice a blue permanent.
Counter target spell.

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.)

Patron Wizard

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

Annul

Counter target artifact or enchantment spell.

Order of the Sacred Torch

{T}, Pay 1 life: Counter target black spell.

Null Elemental Blast

Choose one —
• Counter target multicolored spell.
• Destroy target multicolored permanent.

Malice

Destroy target nonblack creature. It can't be regenerated.

Spite

Spite // Malice

Benevolent Geist

Flying
Noncreature spells you control can't be countered.
If Benevolent Geist would be put into a graveyard from anywhere, exile it instead.

Malevolent Hermit

{U}, Sacrifice this creature: Counter target noncreature spell unless its controller pays {3}.
Disturb {2}{U} (You may cast this card from your graveyard transformed for its disturb cost.)

Malevolent Hermit // Benevolent Geist

Soratami Savant

Flying
{3}, Return a land you control to its owner's hand: Counter target spell unless its controller pays {3}.

Fugitive Droid

This creature can't be blocked if an artifact entered the battlefield under your control this turn.
{U}, Sacrifice this creature: Counter target spell that targets an artifact or creature you control.

Voidmage Prodigy

{U}{U}, Sacrifice a Wizard: Counter target spell.
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.)

Diversion Unit

Flying
{U}, Sacrifice this creature: Counter target instant or sorcery spell unless its controller pays {3}.

Island

Judge's Familiar

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

Mundungu

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

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.)

Rakshasa's Disdain

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

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.

Ertai Resurrected

Flash
When Ertai Resurrected enters, choose up to one —
• Counter target spell, activated ability, or triggered ability. Its controller draws a card.
• Destroy another target creature or planeswalker. Its controller draws a card.