Have

Arcane Signet

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

Desmond Miles

Menace
Desmond Miles gets +1/+0 for each other Assassin you control and each Assassin card in your graveyard.
Whenever Desmond Miles deals combat damage to a player, surveil X, where X is the amount of damage it dealt to that player.

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.

Escarpment Fortress

Defender (This creature can't attack.)
Reach (This creature can block creatures with flying.)
Other creatures you control get +1/+0.
Whenever you attack with two or more creatures, draw a card.

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.

Desynchronization

Return each nonland permanent that's not historic to its owner's hand. (Artifacts, legendaries, and Sagas are historic.)

Bleeding Effect

At the beginning of combat on your turn, creatures you control gain flying until end of turn if a creature card in your graveyard has flying. The same is true for first strike, double strike, deathtouch, hexproof, indestructible, lifelink, menace, reach, trample, and vigilance.

Exotic Orchard

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

Gilded Lotus

Assassin Den

Defender (This creature can't attack.)
{3}{U}: Put a +1/+1 counter on target creature you control. It can't be blocked this turn. Activate only as a sorcery.

Mountain

Brotherhood Patriarch

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

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.

Cover of Darkness

As Cover of Darkness enters, choose a creature type.
Creatures of the chosen type have fear. (They can't be blocked except by artifact creatures and/or black creatures.)

Terminate

Destroy target creature. It can't be regenerated.

Eivor, Battle-Ready

Vigilance (Attacking doesn't cause this creature to tap.)
Haste (This creature can attack as soon as it comes under your control.)
Whenever Eivor, Battle-Ready attacks, it deals damage equal to the number of Equipment you control to each opponent.

Misthios's Fury

Misthios's Fury deals 3 damage to target creature. If you control an Equipment, Misthios's Fury also deals 2 damage to that creature's controller.

Bayek of Siwa

Double strike
During your turn, other historic creatures you control have double strike.
Disguise {1}{R}{W} (You may cast this card face down for {3} as a 2/2 creature with ward {2}. Turn it face up any time for its disguise cost.)

Mortify

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.

Cavern of Souls

As Cavern of Souls enters, choose a creature type.
{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to cast a creature spell of the chosen type, and that spell can't be countered.

Reliquary Tower

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

Chain Assassination

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.)
Destroy target creature. If another creature died this turn, draw a card.

Swords to Plowshares

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

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.)

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.)

Hired Blade

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

Layla Hassan

First strike
When Layla Hassan enters and whenever one or more Assassins you control deal combat damage to a player, return target historic card from your graveyard to your hand.

Retreat to Kazandu

Landfall — Whenever a land you control enters, choose one —
• Put a +1/+1 counter on target creature.
• You gain 2 life.

Ezio, Brash Novice

Whenever Ezio, Brash Novice attacks, put a +1/+1 counter on it.
As long as Ezio has two or more counters on it, it has first strike and is an Assassin in addition to its other types.

Rogue's Passage

{T}: Add {C}.
{4}, {T}: Target creature can't be blocked this turn.

Hedron Archive

{T}: Add {C}{C}.
{2}, {T}, Sacrifice this artifact: Draw two cards.

Restart Sequence

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.)
Return target creature card from your graveyard to the battlefield.

Farseek

Search your library for a Plains, Island, Swamp, or Mountain card, put it onto the battlefield tapped, then shuffle.

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.

Tread Upon

Target creature gets +2/+2 and gains trample until end of turn.

Rooftop Bypass

Whenever one or more nontoken creatures you control deal combat damage to a player, create a 1/1 black Assassin creature token with menace. (It can't be blocked except by two or more creatures.)

Arbaaz Mir

Whenever Arbaaz Mir or another nontoken historic permanent you control enters, Arbaaz Mir deals 1 damage to each opponent and you gain 1 life. (Artifacts, legendaries, and Sagas are historic.)

Assassin Gauntlet

When Assassin Gauntlet enters, attach it to up to one target creature you control. Tap all creatures target opponent controls.
Equipped creature gets +1/+1 and has "Whenever this creature deals combat damage to a player, draw a card, then discard a card."
Equip {2}

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.

Forest

Brotherhood Regalia

Equipped creature has ward {2}, is an Assassin in addition to its other types, and can't be blocked.
Equip legendary creature {1}
Equip {3} ({3}: Attach to target creature you control. Equip only as a sorcery.)

Bureau Headmaster

Equipment spells you cast cost {1} less to cast.
Equip abilities you activate cost {1} less to activate.

Overpowering Attack

Freerunning {2}{R} (You may cast this spell for its freerunning cost if you dealt combat damage to a player this turn with an Assassin or commander.)
Untap all creatures you control that attacked this turn. If it's your main phase, there is an additional combat phase after this phase, followed by an additional main phase.

Morophon, the Boundless

Changeling (This card is every creature type.)
As Morophon, the Boundless enters, 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.

Urborg, Tomb of Yawgmoth

Each land is a Swamp in addition to its other land types.

Chromatic Lantern

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

Battlefield Improvisation

Target creature gets +2/+2 until end of turn. If that creature is attacking, you may attach any number of Equipment you control to it.

Caduceus, Staff of Hermes

Equipped creature has lifelink.
As long as you have 30 or more life, equipped creature gets +5/+5 and has indestructible and "Prevent all damage that would be dealt to this creature."
Equip {W}{W}

Queen Marchesa

Deathtouch, haste
When Queen Marchesa enters, 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.

Swamp

Basim Ibn Ishaq

Whenever you cast a historic spell, draw a card. Basim Ibn Ishaq can't be blocked this turn. This ability triggers only once each turn. (Artifacts, legendaries, and Sagas are historic.)
Whenever Basim Ibn Ishaq deals combat damage to a player, put a +1/+1 counter on it.

Black Market Connections

At the beginning of your first main phase, choose one or more —
• Sell Contraband — Create a Treasure token. You lose 1 life.
• Buy Information — Draw a card. You lose 2 life.
• Hire a Mercenary — Create a 3/2 colorless Shapeshifter creature token with changeling. You lose 3 life. (It has every creature type.)

Assassin's Trophy

Destroy target permanent an opponent controls. Its controller may search their library for a basic land card, put it onto the battlefield, then shuffle.

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.)

Arno Dorian

Deathtouch
Other Assassins you control get +2/+0.
Disguise {B}{R} (You may cast this card face down for {3} as a 2/2 creature with ward {2}. Turn it face up any time for its disguise cost.)

Harrow

As an additional cost to cast this spell, sacrifice a land.
Search your library for up to two basic land cards, put them onto the battlefield, then shuffle.

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.)

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.

Cultivate

Search your library for up to two basic land cards, reveal those cards, put one onto the battlefield tapped and the other into your hand, then shuffle.

Explosive Vegetation

Search your library for up to two basic land cards, put them onto the battlefield tapped, then shuffle.

Sheltered Aerie

Enchant land
Enchanted land has "{T}: Add two mana of any one color."

Hidden Blade

Flash
When Hidden Blade enters, attach it to target creature you control. If that creature is an Assassin, it gains deathtouch until end of turn.
Equipped creature gets +1/+0 and has first strike.
Equip {2}

Achilles Davenport

Freerunning {U}{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.)
Menace (This creature can't be blocked except by two or more creatures.)
Other Assassins you control get +1/+1.

Island

Surtr, Fiery Jötun

Trample (This creature can deal excess combat damage to the player it's attacking.)
Whenever you cast a historic spell, Surtr, Fiery Jötun deals 3 damage to any target. (Artifacts, legendaries, and Sagas are historic.)

Murder

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."

Herald's Horn

As Herald's Horn enters, 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.

Headsplitter

When Headsplitter enters, create a 1/1 black Assassin creature token with menace, then attach Headsplitter to it.
Equipped creature gets +1/+0.
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

Hookblade

When Hookblade enters, attach it to target creature you control.
Equipped creature gets +1/+0.
During your turn, equipped creature has flying.
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

Plains

Eagle Vision

Freerunning {1}{U} (You may cast this spell for its freerunning cost if you dealt combat damage to a player this turn with an Assassin or commander.)
Draw three cards.

Towering Viewpoint

Defender, reach
Leap of Faith — {3}: Target creature gains flying until end of turn.

Aya of Alexandria

Menace, lifelink
Whenever a historic creature you control deals combat damage to a player, create a 1/1 black Assassin creature token with menace. (Artifacts, legendaries, and Sagas are historic.)

Hookblade Veteran

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

Sol Ring

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.

Shao Jun

Leap Strike — During your turn, Shao Jun has flying and first strike.
Rope Dart — Tap two untapped artifacts you control: Shao Jun deals 1 damage to each opponent.

Natural Connection

Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.