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.)

Hookblade Veteran

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

Island

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.)

Swamp

Midnight Assassin

Flying
Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)

Arcane Signet

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

Satoru, the Infiltrator

Menace
Whenever Satoru and/or one or more other nontoken creatures you control enter, if none of them were cast or no mana was spent to cast them, draw a card.

Shadow, Mysterious Assassin

Deathtouch
Throw — Whenever Shadow deals combat damage to a player, you may sacrifice another nonland permanent. If you do, draw two cards and each opponent loses life equal to the mana value of the sacrificed permanent.

Raven Eagle

Flying
Whenever this creature enters or attacks, exile up to one target card from a graveyard. If a creature card is exiled this way, create a Clue token. (It's an artifact with "{2}, Sacrifice this token: Draw a card.")
Whenever you draw your second card each turn, each opponent loses 1 life and you gain 1 life.

Brotherhood Spy

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

Wan Shi Tong, Librarian

Flash
Flying, vigilance
When Wan Shi Tong enters, put X +1/+1 counters on him. Then draw half X cards, rounded down.
Whenever an opponent searches their library, put a +1/+1 counter on Wan Shi Tong and draw a card.

Etrata, Deadly Fugitive

Deathtouch
Face-down creatures you control have "{2}{U}{B}: Turn this creature face up. If you can't, exile it, then you may cast the exiled card without paying its mana cost."
Whenever an Assassin you control deals combat damage to an opponent, cloak the top card of that player's library.

Changeling Outcast

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

Poison-Blade Mentor

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

Aven Heartstabber

Flying
As long as there are five or more mana values among cards in your graveyard, this creature gets +2/+2 and has deathtouch.
When this creature dies, mill two cards, then draw a card.

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 this creature is turned face up, target player loses 2 life.

Secret Tunnel

This land can't be blocked.
{T}: Add {C}.
{4}, {T}: Two target creatures you control that share a creature type can't be blocked this turn.

Massacre Girl

Menace
When Massacre Girl enters, 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.

Etrata, the Silencer

Etrata 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.

Waterbender Ascension

Whenever a creature you control deals combat damage to a player, put a quest counter on this enchantment. Then if it has four or more quest counters on it, draw a card.
Waterbend {4}: Target creature can't be blocked this turn. (While paying a waterbend cost, you can tap your artifacts and creatures to help. Each one pays for {1}.)

Evie Frye

Partner with Jacob Frye (When this creature enters, target player may put Jacob into their hand from their library, then shuffle.)
{1}, {T}: Draw a card, then discard a card. When you discard a creature card this way, target creature you control can't be blocked this turn.

Silumgar Assassin

Creatures with power greater than this creature's power can't block it.
Megamorph {2}{B} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its megamorph cost and put a +1/+1 counter on it.)
When this creature is turned face up, destroy target creature with power 3 or less an opponent controls.

The Blue Spirit

You may cast the first creature spell you cast each turn as though it had flash.
Whenever a nontoken creature you control enters during combat, draw a card.

Leyline of Transformation

If this card is in your opening hand, you may begin the game with it on the battlefield.
As this enchantment enters, choose a creature type.
Creatures you control are the chosen type 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.

Hired Poisoner

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.

Sol Ring

Guildsworn Prowler

Deathtouch
When this creature dies, if it wasn't blocking, draw a card.

Royal Assassin

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.

Ravenloft Adventurer

When this creature enters, you take the initiative.
If a creature an opponent controls would die, instead exile it and put a hit counter on it.
Whenever this creature attacks, if you've completed a dungeon, defending player loses 1 life for each card they own in exile with a hit counter on it.

They Came from the Pipes

When this enchantment enters, manifest dread twice. (To manifest dread, look at the top two cards of your library. Put one onto the battlefield face down as a 2/2 creature and the other into your graveyard. Turn it face up any time for its mana cost if it's a creature card.)
Whenever a face-down creature you control enters, draw a card.

Assassin Initiate

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

Big Game Hunter

When this creature enters, destroy target creature with power 4 or greater. It can't be regenerated.
Madness {B} (If you discard this card, discard it into exile. When you do, cast it for its madness cost or put it into your graveyard.)

Thieving Amalgam

At the beginning of each opponent's upkeep, you manifest the top card of that player's library. (Put it onto the battlefield face down as a 2/2 creature. Turn it face up any time for its mana cost if it's a creature card.)
Whenever a creature you control but don't own dies, its owner loses 2 life and you gain 2 life.

Jacob Frye

Partner with Evie Frye (When this creature enters, target player may put Evie into their hand from their library, then shuffle.)
Whenever one or more Assassins you control deal combat damage to a player, exile up to one target Assassin card or card with freerunning from your graveyard. If you do, copy it. You may cast the copy.

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.

Hullcarver

Omen Hawker

{T}: Add {C}{U}. Spend this mana only to activate abilities.

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.