Reject Imperfection

Counter target spell. If that spell's mana value was 3 or less, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Vexing Bauble

Whenever a player casts a spell, if no mana was spent to cast it, counter that spell.
{1}, {T}, Sacrifice this artifact: Draw a card.

Archaeomancer

When this creature enters, return target instant or sorcery card from your graveyard to your hand.

High Tide

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

Access Denied

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

Neurok Commando

Shroud (This creature can't be the target of spells or abilities.)
Whenever this creature deals combat damage to a player, you may draw a card.

Ghostly Flicker

Exile two target artifacts, creatures, and/or lands you control, then return those cards to the battlefield under your control.

Mana Leak

Counter target spell unless its controller pays {3}.

Silent Hallcreeper

This creature can't be blocked.
Whenever this creature deals combat damage to a player, choose one that hasn't been chosen —
• Put two +1/+1 counters on this creature.
• Draw a card.
• This creature becomes a copy of another target creature you control.

Reliquary Tower

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

Tranquilize

Tap target creature an opponent controls and put three stun counters on it. (If a permanent with a stun counter would become untapped, remove one from it instead.)

Hydroblast

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

Ghastly Haunting

Enchant creature
You control enchanted creature.

Soul Seizer

Flying
When this creature deals combat damage to a player, you may transform it. If you do, attach it to target creature that player controls.

Soul Seizer // Ghastly Haunting

Counterspell

Misdirection

You may exile a blue card from your hand rather than pay this spell's mana cost.
Change the target of target spell with a single target.

Reconnaissance Mission

Whenever a creature you control deals combat damage to a player, you may draw a card.
Cycling {2} ({2}, Discard this card: Draw a card.)

Scroll Thief

Whenever this creature deals combat damage to a player, draw a card.

Muddle the Mixture

Counter target instant or sorcery spell.
Transmute {1}{U}{U} ({1}{U}{U}, Discard this card: Search your library for a card with the same mana value as this card, reveal it, put it into your hand, then shuffle. Transmute only as a sorcery.)

Utter Insignificance

Flash
Enchant creature
Enchanted creature loses all abilities and has base power and toughness 1/1.
{2}{C}: Exile enchanted creature.

Aetherspouts

For each attacking creature, its owner puts it on their choice of the top or bottom of their library.

Sapphire Medallion

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

Disdainful Stroke

Counter target spell with mana value 4 or greater.

Thousand-Faced Shadow

Ninjutsu {2}{U}{U} ({2}{U}{U}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.)
Flying
When this creature enters from your hand, if it's attacking, create a token that's a copy of another target attacking creature. The token enters tapped and attacking.

Arm with Aether

Until end of turn, creatures you control gain "Whenever this creature deals damage to an opponent, you may return target creature that player controls to its owner's hand."

Sinister Sabotage

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

Bitter Chill

Enchant creature
When this Aura enters, tap enchanted creature.
Enchanted creature doesn't untap during its controller's untap step.
When this Aura is put into a graveyard from the battlefield, you may pay {1}. If you do, scry 1, then draw a card.

Dream Fracture

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

Thought Vessel

Voyage's End

Return target creature to its owner's hand. Scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Deep Analysis

Target player draws two cards.
Flashback—{1}{U}, Pay 3 life. (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.

Raven Guild Master

Whenever this creature deals combat damage to a player, that player exiles the top ten cards of their library.
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.)

Stasis Field

Enchant creature
Enchanted creature has base power and toughness 0/2, has defender, and loses all other abilities.

Emrakul's Messenger

Devoid (This card has no color.)
Flying
Whenever you draw your second card each turn, create a 0/1 colorless Eldrazi Spawn creature token with "Sacrifice this token: Add {C}."

Quietus Spike

Equipped creature has deathtouch.
Whenever equipped creature deals combat damage to a player, that player loses half their life, rounded up.
Equip {3}

Cancel

Spell Pierce

Counter target noncreature spell unless its controller pays {2}.

Lazotep Plating

Amass Zombies 1. (Put a +1/+1 counter on an Army you control. It's also a Zombie. If you don't control an Army, create a 0/0 black Zombie Army creature token first.)
You and permanents you control gain hexproof until end of turn. (You and they can't be the targets of spells or abilities your opponents control.)

Cephalid Facetaker

This creature can't be blocked.
At the beginning of combat on your turn, you may have this creature become a copy of another target creature until end of turn, except it's 1/4 and has "This creature can't be blocked."

Surrakar Spellblade

Whenever you cast an instant or sorcery spell, you may put a charge counter on this creature.
Whenever this creature deals combat damage to a player, you may draw X cards, where X is the number of charge counters on it.

Exclude

Counter target creature spell.
Draw a card.

Wizards of Thay

Myriad (Whenever this creature attacks, for each opponent other than defending player, you may create a token copy that's tapped and attacking that player or a planeswalker they control. Exile the tokens at end of combat.)
Instant and sorcery spells you cast cost {1} less to cast.
You may cast sorcery spells as though they had flash.

Mist-Syndicate Naga

Ninjutsu {2}{U} ({2}{U}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.)
Whenever this creature deals combat damage to a player, create a token that's a copy of this creature.

Aetherize

Return all attacking creatures to their owner's hand.

Dreamshackle Geist

Flying
At the beginning of combat on your turn, choose up to one —
• Tap target creature.
• Target creature doesn't untap during its controller's next untap step.

Thieving Skydiver

Kicker {X}. X can't be 0. (You may pay an additional {X} as you cast this spell.)
Flying
When this creature enters, if it was kicked, gain control of target artifact with mana value X or less. If that artifact is an Equipment, attach it to this creature.

Mocking Sprite

Flying
Instant and sorcery spells you cast cost {1} less to cast.

Island

Whirler Rogue

When this creature enters, create two 1/1 colorless Thopter artifact creature tokens with flying.
Tap two untapped artifacts you control: Target creature can't be blocked this turn.

Tetsuko Umezawa, Fugitive

Creatures you control with power or toughness 1 or less can't be blocked.

Esior, Wardwing Familiar

Flying
Spells your opponents cast that target one or more commanders you control cost {3} more to cast.
Partner (You can have two commanders if both have partner.)

Arcane Signet

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

Repulse

Return target creature to its owner's hand.
Draw a card.

Murmuring Mystic

Whenever you cast an instant or sorcery spell, create a 1/1 blue Bird Illusion creature token with flying.

Aether Channeler

When this creature enters, choose one —
• Create a 1/1 white Bird creature token with flying.
• Return another target nonland permanent to its owner's hand.
• Draw a card.

Hermitic Nautilus

Vigilance
{1}{U}: This creature gets +3/-3 until end of turn.

Malcolm, Alluring Scoundrel

Flash
Flying
Whenever Malcolm deals combat damage to a player, put a chorus counter on it. Draw a card, then discard a card. If there are four or more chorus counters on Malcolm, you may cast the discarded card without paying its mana cost.

Rewind

Counter target spell. Untap up to four lands.

Tale's End

Counter target activated ability, triggered ability, or legendary spell.

Master of Waves

Protection from red
Elemental creatures you control get +1/+1.
When this creature enters, create a number of 1/0 blue Elemental creature tokens equal to your devotion to blue. (Each {U} in the mana costs of permanents you control counts toward your devotion to blue.)

An Offer You Can't Refuse

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

Excalibur, Sword of Eden

This spell costs {X} less to cast, where X is the total mana value of historic permanents you control. (Artifacts, legendaries, and Sagas are historic.)
Equipped creature gets +10/+0 and has vigilance.
Equip legendary creature {2}

Negate

Spellseeker

When this creature enters, 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.

Mistblade Shinobi

Ninjutsu {U} ({U}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.)
Whenever this creature deals combat damage to a player, you may return target creature that player controls to its owner's hand.

Sol Ring

Bounce Off

Return target creature or Vehicle to its owner's hand.

Wash Out

Return all permanents of the color of your choice to their owners' hands.

Portal Mage

Flash
When this creature enters during the declare attackers step, you may reselect which player or permanent target attacking creature is attacking. (It can't attack its controller or their permanents.)