Tekuthal, Inquiry Dominus

Flying
If you would proliferate, proliferate twice instead.
{1}{U/P}{U/P}, Remove three counters from among other artifacts, creatures, and planeswalkers you control: Put an indestructible counter on Tekuthal, Inquiry Dominus. ({U/P} can be paid with either {U} or 2 life.)

Tyrant's Scorn

Choose one —
• Destroy target creature with mana value 3 or less.
• Return target creature to its owner's hand.

Armored Armadillo

Ward {1} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {1}.)
{3}{W}: Armored Armadillo gets +X/+0 until end of turn, where X is its toughness.

Towering Viewpoint

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

Island

Blacksnag Buzzard

Flying
Blacksnag Buzzard enters with a +1/+1 counter on it if a creature died this turn.
Plot {1}{B} (You may pay {1}{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.)

Sanitation Automaton

When Sanitation Automaton enters, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)

Sterling Keykeeper

Submerged Boneyard

Submerged Boneyard enters tapped.
{T}: Add {U} or {B}.

Pearl of Wisdom

This spell costs {1} less to cast if you control an Otter.
Draw two cards.

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.

Swamp

Reasonable Doubt

Counter target spell unless its controller pays {2}.
Suspect up to one target creature. (A suspected creature has menace and can't block.)

Plains

Luxurious Locomotive

Whenever Luxurious Locomotive attacks, create a Treasure token for each creature that crewed it this turn. (They're artifacts with "{T}, Sacrifice this artifact: Add one mana of any color.")
Crew 1. Activate only once each turn. (Tap any number of creatures you control with total power 1 or more: This Vehicle becomes an artifact creature until end of turn.)

Bounding Felidar

Whenever Bounding Felidar attacks while saddled, put a +1/+1 counter on each other creature you control. You gain 1 life for each of those creatures.
Saddle 2 (Tap any number of other creatures you control with total power 2 or more: This Mount becomes saddled until end of turn. Saddle only as a sorcery.)

Blightbelly Rat

Toxic 1 (Players dealt combat damage by this creature also get a poison counter.)
When Blightbelly Rat dies, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Karlov Watchdog

Vigilance
Permanents your opponents control can't be turned face up during your turn.
Whenever you attack with three or more creatures, creatures you control get +1/+1 until end of turn.

Lonely Arroyo

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

Assassin Initiate

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

Loyal Inventor

Vigilance
When Loyal Inventor enters, you may search your library for an artifact card, reveal it, then shuffle. Put that card into your hand if you control an Assassin. Otherwise, put that card on top of your library.

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.

Archive Dragon

Flying
Ward {2} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {2}.)
When Archive Dragon enters, scry 2.

Sword of Vengeance

Equipped creature gets +2/+0 and has first strike, vigilance, trample, and haste.
Equip {3}

Repel Calamity

Destroy target creature with power or toughness 4 or greater.

Flusterstorm

Counter target instant or sorcery spell unless its controller pays {1}.
Storm (When you cast this spell, copy it for each spell cast before it this turn. You may choose new targets for the copies.)

Fountainport Bell

When Fountainport Bell enters, you may search your library for a basic land card, reveal it, then shuffle and put that card on top.
{1}, Sacrifice Fountainport Bell: Draw a card.

Ossification

Enchant basic land you control
When Ossification enters, exile target creature or planeswalker an opponent controls until Ossification leaves the battlefield.

Boon-Bringer Valkyrie

Backup 1 (When this creature enters, put a +1/+1 counter on target creature. If that's another creature, it gains the following abilities until end of turn.)
Flying, first strike, lifelink

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.

Belenon War Anthem

Invasion of Belenon

(As a Siege enters, choose an opponent to protect it. You and others can attack it. When it's defeated, exile it, then cast it transformed.)
When Invasion of Belenon enters, create a 2/2 white and blue Knight creature token with vigilance.

Invasion of Belenon // Belenon War Anthem

Rakish Crew

When Rakish Crew enters, create a 1/1 red Mercenary creature token with "{T}: Target creature you control gets +1/+0 until end of turn. Activate only as a sorcery."
Whenever an outlaw you control dies, each opponent loses 1 life and you gain 1 life. (Assassins, Mercenaries, Pirates, Rogues, and Warlocks are outlaws.)

Cooped Up

Enchant creature
Enchanted creature can't attack or block.
{2}{W}: Exile enchanted creature.

Unscrupulous Agent

When Unscrupulous Agent enters, target opponent exiles a card from their hand.

Mirage Mesa

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

Carrot Cake

When Carrot Cake enters and when you sacrifice it, create a 1/1 white Rabbit creature token and scry 1. (Look at the top card of your library. You may put that card on the bottom.)
{2}, {T}, Sacrifice Carrot Cake: You gain 3 life.

Sen Triplets

At the beginning of your upkeep, choose target opponent. This turn, that player can't cast spells or activate abilities and plays with their hand revealed. You may play lands and cast spells from that player's hand this turn.

Seven-Tail Mentor

When Seven-Tail Mentor enters or dies, put a +1/+1 counter on target creature or Vehicle you control.

Shay Cormac

{1}: Permanents your opponents control lose hexproof, indestructible, protection, shroud, and ward until end of turn.
Whenever a creature an opponent controls becomes the target of a spell or ability you control, put a bounty counter on that creature.
Whenever a creature with a bounty counter on it dies, put two +1/+1 counters on Shay Cormac.

Evolving Wilds

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

Prairie Dog

Lifelink
At the beginning of your end step, if you haven't cast a spell from your hand this turn, put a +1/+1 counter on Prairie Dog.
{4}{W}: Until end of turn, if you would put one or more +1/+1 counters on a creature you control, put that many plus one +1/+1 counters on it instead.

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.)

Daring Thunder-Thief

Flash
Daring Thunder-Thief enters tapped.

Quick Study

Adarkar Wastes

{T}: Add {C}.
{T}: Add {W} or {U}. Adarkar Wastes deals 1 damage to you.

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}

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}.

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.)

Thriving Heath

Thriving Heath enters tapped. As it enters, choose a color other than white.
{T}: Add {W} or one mana of the chosen color.

Auditore Ambush

Choose one or both —
• Return target creature to its owner's hand.
• Target player searches their library and/or graveyard for a card named Ezio, Blade of Vengeance, reveals it, and puts it into their hand. If they search their library this way, they shuffle.

Rattleback Apothecary

Deathtouch
Whenever you commit a crime, target creature you control gains your choice of menace or lifelink until end of turn. (Targeting opponents, anything they control, and/or cards in their graveyards is a crime.)

Exit Specialist

Exit Specialist can't be blocked by creatures with power 3 or greater.
Disguise {1}{U} (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.)
When Exit Specialist is turned face up, return another target creature to its owner's hand.

Thunder Lasso

When Thunder Lasso enters, attach it to target creature you control.
Equipped creature gets +1/+1.
Whenever equipped creature attacks, tap target creature defending player controls.
Equip {2}

Eriette's Lullaby

Destroy target tapped creature. You gain 2 life.

Mind Spring

Waterspout Warden

Whenever Waterspout Warden attacks, if another creature entered the battlefield under your control this turn, Waterspout Warden gains flying until end of turn.

Brotherhood Patriarch

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

Take Up the Shield

Put a +1/+1 counter on target creature. It gains lifelink and indestructible until end of turn. (Damage and effects that say "destroy" don't destroy it.)

Hop to It

Create three 1/1 white Rabbit creature tokens.

Mockingbird

Flying
You may have Mockingbird enter as a copy of any creature on the battlefield with mana value less than or equal to the amount of mana spent to cast Mockingbird, except it's a Bird in addition to its other types and it has flying.

Detained by Legionnaires

Enchant creature
Enchanted creature can't attack or block.

Stasis Field

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

Glacial Fortress

Glacial Fortress enters tapped unless you control a Plains or an Island.
{T}: Add {W} or {U}.

Murder

Errant and Giada

Flash
Flying
You may look at the top card of your library any time.
You may cast spells with flash or flying from the top of your library.

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.)

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.

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.

Hidden Grotto

When Hidden Grotto enters, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)
{T}: Add {C}.
{1}, {T}: Add one mana of any color.

Consuming Ashes

Exile target creature. If it had mana value 3 or less, surveil 2. (Look at the top two cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)

Dust Bowl

{T}: Add {C}.
{3}, {T}, Sacrifice a land: Destroy target nonbasic land.

In the Trenches

Creatures you control get +1/+1.
{5}{W}: Exile target nonland permanent you don't control until In the Trenches leaves the battlefield. Activate only as a sorcery and only once.

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.

Ingenious Prodigy

Skulk (This creature can't be blocked by creatures with greater power.)
Ingenious Prodigy enters with X +1/+1 counters on it.
At the beginning of your upkeep, if Ingenious Prodigy has one or more +1/+1 counters on it, you may remove a +1/+1 counter from it. If you do, draw a card.

Mesa Cavalier

Flying
When Mesa Cavalier enters, you gain 2 life.

Soulless Jailer

Permanent cards in graveyards can't enter the battlefield.
Players can't cast noncreature spells from graveyards or exile.