Tainted Strike

Target creature gets +1/+0 and gains infect until end of turn. (It deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)

Poison-Blade Mentor

Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)
Whenever Poison-Blade Mentor attacks, another target Assassin you control gains deathtouch until end of turn.

Vraska's Fall

Each opponent sacrifices a creature or planeswalker and gets a poison counter.

Dismal Backwater

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

Counterspell

Brotherhood Spy

At the beginning of combat on your turn, if you control a legendary Assassin, Brotherhood Spy gets +1/+0 until end of turn and can't be blocked this turn.

Hookblade Veteran

During your turn, Hookblade Veteran has flying. (It can't be blocked except by creatures with flying or reach.)

Orzhov Euthanist

Haunt (When this creature dies, exile it haunting target creature.)
When Orzhov Euthanist enters or the creature it haunts dies, destroy target creature that was dealt damage this turn.

Skeletal Changeling

Changeling (This card is every creature type.)
{1}{B}: Regenerate Skeletal Changeling.

Stingblade Assassin

Flash
Flying
When Stingblade Assassin enters, destroy target creature an opponent controls that was dealt damage this turn.

Assassin Initiate

{1}: Assassin Initiate gains your choice of flying, deathtouch, or lifelink until end of turn.

Island

Venomous Changeling

Changeling (This card is every creature type.)
Deathtouch

Aqueous Form

Enchant creature
Enchanted creature can't be blocked.
Whenever enchanted creature attacks, scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Roshan, Hidden Magister

Other creatures you control are Assassins in addition to their other types. The same is true for creature spells you control and creature cards you own that aren't on the battlefield.
Face-down creatures you control have menace.
Whenever a permanent you control is turned face up, you draw a card and you lose 1 life.

Vraska's Finisher

When Vraska's Finisher enters, destroy target creature or planeswalker an opponent controls that was dealt damage this turn.

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.)

Ruthless Ripper

Deathtouch
Morph—Reveal a black card in your hand. (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 Ruthless Ripper is turned face up, target player loses 2 life.

Read the Bones

Scry 2, then draw two cards. You lose 2 life.

Changeling Outcast

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

Contaminated Aquifer

({T}: Add {U} or {B}.)
Contaminated Aquifer enters tapped.

Whisper of the Dross

Target creature gets -1/-1 until end of turn. Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Brotherhood Ambushers

Freerunning {3}{B} (You may cast this spell for its freerunning cost if you dealt combat damage to a player this turn with an Assassin or commander.)

Prologue to Phyresis

Each opponent gets a poison counter.
Draw a card.

Lydia Frye

Lydia Frye can't be blocked by creatures with power 3 or greater.
At the beginning of your end step, surveil X, where X is the number of tapped Assassins you control. (Look at the top X cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)

Brotherhood Patriarch

When Brotherhood Patriarch dies, each opponent loses 2 life and you gain 2 life.

Commander's Sphere

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

Ponder

Look at the top three cards of your library, then put them back in any order. You may shuffle.
Draw a card.

Soured Springs

Soured Springs enters tapped.
When Soured Springs enters, it deals 1 damage to target opponent.
{T}: Add {U} or {B}.

Suq'Ata Assassin

Fear (This creature can't be blocked except by artifact creatures and/or black creatures.)
Whenever Suq'Ata Assassin attacks and isn't blocked, defending player gets a poison counter. (A player with ten or more poison counters loses the game.)

Hired Blade

Flash (You may cast this spell any time you could cast an instant.)

Hooded Assassin

When Hooded Assassin enters, choose one —
• Put a +1/+1 counter on Hooded Assassin.
• Destroy target creature that was dealt damage this turn.

Nirkana Assassin

Whenever you gain life, Nirkana Assassin gains deathtouch until end of turn. (Any amount of damage it deals to a creature is enough to destroy it.)

Guildsworn Prowler

Deathtouch
When Guildsworn Prowler dies, if it wasn't blocking, draw a card.

Dark Ritual

Lurking Deadeye

Flash
When Lurking Deadeye enters, destroy target creature that was dealt damage this turn.

Negate

Sky Diamond

Infectious Inquiry

You draw two cards and you lose 2 life. Each opponent gets a poison counter.

Rooftop Assassin

Flash
Flying, lifelink
When Rooftop Assassin enters, destroy target creature an opponent controls that was dealt damage this turn.

Eyeblight Assassin

When Eyeblight Assassin enters, target creature an opponent controls gets -1/-1 until end of turn.

Cloak of Mists

Enchant creature
Enchanted creature can't be blocked.

Swamp

Thorn of the Black Rose

Deathtouch
When Thorn of the Black Rose enters, you become the monarch.

Merciless Harlequin

Freerunning {1}{B} (You may cast this spell for its freerunning cost if you dealt combat damage to a player this turn with an Assassin or commander.)
When Merciless Harlequin enters, you draw a card and you lose 1 life.

Terramorphic Expanse

{T}, Sacrifice Terramorphic Expanse: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Unscrupulous Contractor

When Unscrupulous Contractor enters, you may sacrifice a creature. When you do, target player draws two cards and loses 2 life.
Plot {2}{B} (You may pay {2}{B} and exile this card from your hand. Cast it as a sorcery on a later turn without paying its mana cost. Plot only as a sorcery.)

Mothdust Changeling

Changeling (This card is every creature type.)
Tap an untapped creature you control: Mothdust Changeling gains flying until end of turn.

Midnight Assassin

Experimental Augury

Look at the top three cards of your library. Put one of them into your hand and the rest on the bottom of your library in any order. Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Thrill-Kill Assassin

Deathtouch
Unleash (You may have this creature enter with a +1/+1 counter on it. It can't block as long as it has a +1/+1 counter on it.)

Path of Ancestry

Path of Ancestry enters 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.)

Arcane Signet

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

Murder

Feed the Swarm

Destroy target creature or enchantment an opponent controls. You lose life equal to that permanent's mana value.

Briarblade Adept

Whenever Briarblade Adept attacks, target creature an opponent controls gets -1/-1 until end of turn.
Encore {3}{B} ({3}{B}, Exile this card from your graveyard: 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.)

Repeat Offender

{2}{B}: If Repeat Offender is suspected, put a +1/+1 counter on it. Otherwise, suspect it. (A suspected creature has menace and can't block.)

Hired Poisoner

Unearth

Return target creature card with mana value 3 or less from your graveyard to the battlefield.
Cycling {2} ({2}, Discard this card: Draw a card.)

Universal Automaton

Changeling (This card is every creature type.)

Kaya's Ghostform

Enchant creature or planeswalker you control
When enchanted permanent dies or is put into exile, return that card to the battlefield under your control.

Distant Melody

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

Gixian Skullflayer

At the beginning of your upkeep, if there are three or more creature cards in your graveyard, put a +1/+1 counter on Gixian Skullflayer.

Charcoal Diamond

Charcoal Diamond enters tapped.
{T}: Add {B}.

Dimir Signet

Mistwalker

Changeling (This card is every creature type.)
Flying
{1}{U}: Mistwalker gets +1/-1 until end of turn.

Sign in Blood

Target player draws two cards and loses 2 life.

Weed-Pruner Poplar

At the beginning of your upkeep, target creature other than Weed-Pruner Poplar gets -1/-1 until end of turn.

Slip Through Space

Devoid (This card has no color.)
Target creature can't be blocked this turn.
Draw a card.

Command Tower

Phyresis

Enchant creature
Enchanted creature has infect. (It deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)

Brainstorm

Draw three cards, then put two cards from your hand on top of your library in any order.

Littjara Kinseekers

Changeling (This card is every creature type.)
When Littjara Kinseekers enters, if you control three or more creatures that share a creature type, put a +1/+1 counter on Littjara Kinseekers, then scry 1.

Birthday Escape

Shadow Rift

Target creature gains shadow until end of turn. (It can block or be blocked by only creatures with shadow.)
Draw a card.

Night's Whisper

Dimir Guildgate

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

Adéwalé, Breaker of Chains

When Adéwalé enters, reveal the top six cards of your library. Put an Assassin, Pirate, or Vehicle card from among them into your hand and the rest on the bottom of your library in a random order.
Whenever a Vehicle you control deals combat damage to a player, you may return Adéwalé from your graveyard to your hand.

Evolving Wilds

{T}, Sacrifice Evolving Wilds: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Moonglove Changeling

Changeling (This card is every creature type.)
{B}: Moonglove Changeling gains deathtouch until end of turn. (Any amount of damage it deals to a creature is enough to destroy that creature.)