Counterspell

Chromatic Lantern

Lands you control have "{T}: Add one mana of any color."
{T}: Add one mana of any color.

Have

Mari, the Killing Quill

Whenever a creature an opponent controls dies, exile it with a hit counter on it.
Assassins, Mercenaries, and Rogues you control have deathtouch and "Whenever this creature deals combat damage to a player, you may remove a hit counter from a card that player owns in exile. If you do, draw a card and create two Treasure tokens."

Sorin Markov

+2: Sorin Markov deals 2 damage to any target and you gain 2 life.
−3: Target opponent's life total becomes 10.
−7: You control target player during that player's next turn.

Graywater's Fixer

Each outlaw creature card in your graveyard has encore {X}, where X is its mana value. (Exile it and pay its encore cost: For each opponent, create a token copy that attacks that opponent this turn if able. They gain haste. Sacrifice them at the beginning of the next end step. Activate only as a sorcery.)

Rakdos Signet

Mirage Mesa

Mirage Mesa enters the battlefield tapped. As it enters, choose a color.
{T}: Add one mana of the chosen color.

Molten Tributary

({T}: Add {U} or {R}.)
Molten Tributary enters the battlefield tapped.

Orzhov Signet

Kelsien, the Plague

Vigilance, haste
Kelsien, the Plague gets +1/+1 for each experience counter you have.
{T}: Kelsien deals 1 damage to target creature you don't control. When that creature dies this turn, you get an experience counter.

Thriving Isle

Thriving Isle enters the battlefield tapped.
As Thriving Isle enters the battlefield, choose a color other than blue.
{T}: Add {U} or one mana of the chosen color.

Swiftwater Cliffs

Swiftwater Cliffs enters the battlefield tapped.
When Swiftwater Cliffs enters the battlefield, you gain 1 life.
{T}: Add {U} or {R}.

Commander's Sphere

{T}: Add one mana of any color in your commander's color identity.
Sacrifice Commander's Sphere: Draw a card.

Brass's Bounty

For each land you control, create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Izzet Guildgate

Izzet Guildgate enters the battlefield tapped.
{T}: Add {U} or {R}.

Dimir Aqueduct

Dimir Aqueduct enters the battlefield tapped.
When Dimir Aqueduct enters the battlefield, return a land you control to its owner's hand.
{T}: Add {U}{B}.

Rain of Riches

When Rain of Riches enters the battlefield, create two Treasure tokens.
The first spell you cast each turn that mana from a Treasure was spent to cast has cascade. (When you cast the spell, exile cards from the top of your library until you exile a nonland card that costs less. You may cast it without paying its mana cost. Put the exiled cards on the bottom in a random order.)

Jodah, Archmage Eternal

Flying
You may pay {W}{U}{B}{R}{G} rather than pay the mana cost for spells that you cast.

Bristling Backwoods

Bristling Backwoods enters the battlefield tapped.
When Bristling Backwoods enters the battlefield, it deals 1 damage to target opponent.
{T}: Add {R} or {G}.

Realmwalker

Changeling (This card is every creature type.)
As Realmwalker enters the battlefield, choose a creature type.
You may look at the top card of your library any time.
You may cast creature spells of the chosen type from the top of your library.

Ezio, Blade of Vengeance

Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)
Whenever an Assassin you control deals combat damage to a player, draw a card.

Blasphemous Act

This spell costs {1} less to cast for each creature on the battlefield.
Blasphemous Act deals 13 damage to each creature.

Jungle Hollow

Jungle Hollow enters the battlefield tapped.
When Jungle Hollow enters the battlefield, you gain 1 life.
{T}: Add {B} or {G}.

Abraded Bluffs

Abraded Bluffs enters the battlefield tapped.
When Abraded Bluffs enters the battlefield, it deals 1 damage to target opponent.
{T}: Add {R} or {W}.

Lonely Arroyo

Lonely Arroyo enters the battlefield tapped.
When Lonely Arroyo enters the battlefield, it deals 1 damage to target opponent.
{T}: Add {W} or {U}.

Temple of Silence

Temple of Silence enters the battlefield tapped.
When Temple of Silence enters the battlefield, scry 1.
{T}: Add {W} or {B}.

Dismal Backwater

Dismal Backwater enters the battlefield tapped.
When Dismal Backwater enters the battlefield, you gain 1 life.
{T}: Add {U} or {B}.

Olivia, Opulent Outlaw

Flying, lifelink
Whenever one or more outlaws you control deal combat damage to a player, create a Treasure token. (Assassins, Mercenaries, Pirates, Rogues, and Warlocks are outlaws.)
{3}, Sacrifice two Treasures: Put two +1/+1 counters on each creature you control. Activate only as a sorcery.

Diabolic Tutor

Search your library for a card, put that card into your hand, then shuffle.

Laboratory Maniac

If you would draw a card while your library has no cards in it, you win the game instead.

Prairie Stream

({T}: Add {W} or {U}.)
Prairie Stream enters the battlefield tapped unless you control two or more basic lands.

Sol Ring

Thriving Bluff

Thriving Bluff enters the battlefield tapped.
As Thriving Bluff enters the battlefield, choose a color other than red.
{T}: Add {R} or one mana of the chosen color.

Training Center

Training Center enters the battlefield tapped unless you have two or more opponents.
{T}: Add {U} or {R}.

Debtors' Knell

({W/B} can be paid with either {W} or {B}.)
At the beginning of your upkeep, put target creature card from a graveyard onto the battlefield under your control.

Path to Exile

Exile target creature. Its controller may search their library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Wose Pathfinder

{T}: Add one mana of any color.
{6}{G}, {T}: Another target creature gets +3/+3 and gains trample until end of turn.

Etrata, the Silencer

Etrata, the Silencer can't be blocked.
Whenever Etrata deals combat damage to a player, exile target creature that player controls and put a hit counter on that card. That player loses the game if they own three or more exiled cards with hit counters on them. Etrata's owner shuffles Etrata into their library.

Callidus Assassin

Flash
Polymorphine — You may have Callidus Assassin enter the battlefield tapped as a copy of any creature on the battlefield, except it has "When this creature enters the battlefield, destroy up to one other target creature with the same name as this creature."

Rodeo Pyromancers

Whenever you cast your first spell each turn, add {R}{R}.

Kindred Dominance

Choose a creature type. Destroy all creatures that aren't of the chosen type.

Temple of Epiphany

Temple of Epiphany enters the battlefield tapped.
When Temple of Epiphany enters the battlefield, scry 1.
{T}: Add {U} or {R}.

Exotic Orchard

{T}: Add one mana of any color that a land an opponent controls could produce.

Rejuvenating Springs

Rejuvenating Springs enters the battlefield tapped unless you have two or more opponents.
{T}: Add {G} or {U}.

Timeless Lotus

Timeless Lotus enters the battlefield tapped.
{T}: Add {W}{U}{B}{R}{G}.

Thraximundar

Haste
Whenever Thraximundar attacks, defending player sacrifices a creature.
Whenever a player sacrifices a creature, you may put a +1/+1 counter on Thraximundar.

Nomad Outpost

Nomad Outpost enters the battlefield tapped.
{T}: Add {R}, {W}, or {B}.

Farewell

Choose one or more —
• Exile all artifacts.
• Exile all creatures.
• Exile all enchantments.
• Exile all graveyards.

Massacre Girl

Menace
When Massacre Girl enters the battlefield, each other creature gets -1/-1 until end of turn. Whenever a creature dies this turn, each creature other than Massacre Girl gets -1/-1 until end of turn.

Dark Impostor

{4}{B}{B}: Exile target creature and put a +1/+1 counter on Dark Impostor.
Dark Impostor has all activated abilities of all creature cards exiled with it.

Altaïr Ibn-La'Ahad

First strike
Whenever Altaïr Ibn-La'Ahad attacks, exile up to one target Assassin creature card from your graveyard with a memory counter on it. Then for each creature card you own in exile with a memory counter on it, create a tapped and attacking token that's a copy of it. Exile those tokens at end of combat.

Orzhov Guildgate

Orzhov Guildgate enters the battlefield tapped.
{T}: Add {W} or {B}.

Dark Ritual

Restless Anchorage

Restless Anchorage enters the battlefield tapped.
{T}: Add {W} or {U}.
{1}{W}{U}: Until end of turn, Restless Anchorage becomes a 2/3 white and blue Bird creature with flying. It's still a land.
Whenever Restless Anchorage attacks, create a Map token.

Massacre Girl, Known Killer

Menace
Creatures you control have wither. (They deal damage to creatures in the form of -1/-1 counters.)
Whenever a creature an opponent controls dies, if its toughness was less than 1, draw a card.

Frostboil Snarl

As Frostboil Snarl enters the battlefield, you may reveal an Island or Mountain card from your hand. If you don't, Frostboil Snarl enters the battlefield tapped.
{T}: Add {U} or {R}.

Dimir Guildgate

Dimir Guildgate enters the battlefield tapped.
{T}: Add {U} or {B}.

Negate

Reliquary Tower

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

Restless Cottage

Restless Cottage enters the battlefield tapped.
{T}: Add {B} or {G}.
{2}{B}{G}: Restless Cottage becomes a 4/4 black and green Horror creature until end of turn. It's still a land.
Whenever Restless Cottage attacks, create a Food token and exile up to one target card from a graveyard.

Temple of Deceit

Temple of Deceit enters the battlefield tapped.
When Temple of Deceit enters the battlefield, scry 1.
{T}: Add {U} or {B}.

Swords to Plowshares

Exile target creature. Its controller gains life equal to its power.

Double Down

Whenever you cast an outlaw spell, copy that spell. (Assassins, Mercenaries, Pirates, Rogues, and Warlocks are outlaws. Copies of permanent spells become tokens.)

Creosote Heath

Creosote Heath enters the battlefield tapped.
When Creosote Heath enters the battlefield, it deals 1 damage to target opponent.
{T}: Add {G} or {W}.

Temple of Triumph

Temple of Triumph enters the battlefield tapped.
When Temple of Triumph enters the battlefield, scry 1.
{T}: Add {R} or {W}.

Virtus the Veiled

Partner with Gorm the Great (When this creature enters the battlefield, target player may put Gorm into their hand from their library, then shuffle.)
Deathtouch
Whenever Virtus the Veiled deals combat damage to a player, that player loses half their life, rounded up.

Herald's Horn

As Herald's Horn enters the battlefield, choose a creature type.
Creature spells you cast of the chosen type cost {1} less to cast.
At the beginning of your upkeep, look at the top card of your library. If it's a creature card of the chosen type, you may reveal it and put it into your hand.

Crystal Grotto

When Crystal Grotto enters the battlefield, scry 1.
{T}: Add {C}.
{1}, {T}: Add one mana of any color.

Path of Ancestry

Path of Ancestry enters the battlefield 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.)

Simic Guildgate

Simic Guildgate enters the battlefield tapped.
{T}: Add {G} or {U}.

Ramses, Assassin Lord

Deathtouch
Other Assassins you control get +1/+1.
Whenever a player loses the game, if they were attacked this turn by an Assassin you controlled, you win the game.

Beast Whisperer

Whenever you cast a creature spell, draw a card.

Restless Vinestalk

Restless Vinestalk enters the battlefield tapped.
{T}: Add {G} or {U}.
{3}{G}{U}: Until end of turn, Restless Vinestalk becomes a 5/5 green and blue Plant creature with trample. It's still a land.
Whenever Restless Vinestalk attacks, up to one other target creature has base power and toughness 3/3 until end of turn.

Twinblade Assassins

At the beginning of your end step, if a creature died this turn, draw a card.

Temple of Malice

Temple of Malice enters the battlefield tapped.
When Temple of Malice enters the battlefield, scry 1.
{T}: Add {B} or {R}.

Command Tower

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

Ezio Auditore da Firenze

Menace
Assassin spells you cast have freerunning {B}{B}. (You may cast a spell for its freerunning cost if you dealt combat damage to a player this turn with an Assassin or commander.)
Whenever Ezio deals combat damage to a player, you may pay {W}{U}{B}{R}{G} if that player has 10 or less life. When you do, that player loses the game.

Smoldering Marsh

({T}: Add {B} or {R}.)
Smoldering Marsh enters the battlefield tapped unless you control two or more basic lands.

Blackcleave Cliffs

Blackcleave Cliffs enters the battlefield tapped unless you control two or fewer other lands.
{T}: Add {B} or {R}.

Distant Melody

Choose a creature type. Draw a card for each permanent you control of that type.

Tree of Perdition

Defender
{T}: Exchange target opponent's life total with Tree of Perdition's toughness.

Queen Marchesa

Deathtouch, haste
When Queen Marchesa enters the battlefield, you become the monarch.
At the beginning of your upkeep, if an opponent is the monarch, create a 1/1 black Assassin creature token with deathtouch and haste.

Morophon, the Boundless

Changeling (This card is every creature type.)
As Morophon, the Boundless enters the battlefield, choose a creature type.
Spells of the chosen type you cast cost {W}{U}{B}{R}{G} less to cast. This effect reduces only the amount of colored mana you pay.
Other creatures you control of the chosen type get +1/+1.

Canopy Vista

({T}: Add {G} or {W}.)
Canopy Vista enters the battlefield tapped unless you control two or more basic lands.

Boros Guildgate

Boros Guildgate enters the battlefield tapped.
{T}: Add {R} or {W}.

Birds of Paradise

Hero's Downfall

Changeling Outcast

Changeling (This card is every creature type.)
Changeling Outcast can't block and can't be blocked.

Rugged Prairie

{T}: Add {C}.
{R/W}, {T}: Add {R}{R}, {R}{W}, or {W}{W}.

Fellwar Stone

Mystic Monastery

Mystic Monastery enters the battlefield tapped.
{T}: Add {U}, {R}, or {W}.

As Foretold

At the beginning of your upkeep, put a time counter on As Foretold.
Once each turn, you may pay {0} rather than pay the mana cost for a spell you cast with mana value X or less, where X is the number of time counters on As Foretold.

Botanical Sanctum

Botanical Sanctum enters the battlefield tapped unless you control two or fewer other lands.
{T}: Add {G} or {U}.

Arcane Signet

Trailblazer's Boots

Equipped creature has nonbasic landwalk. (It can't be blocked as long as defending player controls a nonbasic land.)
Equip {2}

Back in Town

Return X target outlaw creature cards from your graveyard to the battlefield. (Assassins, Mercenaries, Pirates, Rogues, and Warlocks are outlaws.)

Propaganda

Creatures can't attack you unless their controller pays {2} for each creature they control that's attacking you.

Sunken Hollow

({T}: Add {U} or {B}.)
Sunken Hollow enters the battlefield tapped unless you control two or more basic lands.

Vanquisher's Banner

As Vanquisher's Banner enters the battlefield, choose a creature type.
Creatures you control of the chosen type get +1/+1.
Whenever you cast a creature spell of the chosen type, draw a card.

Vraska the Unseen

+1: Until your next turn, whenever a creature deals combat damage to Vraska the Unseen, destroy that creature.
−3: Destroy target nonland permanent.
−7: Create three 1/1 black Assassin creature tokens with "Whenever this creature deals combat damage to a player, that player loses the game."