Scrapdiver Serpent

Scrapdiver Serpent can't be blocked as long as defending player controls an artifact.

Necrobite

Target creature gains deathtouch until end of turn. Regenerate it. (The next time that creature would be destroyed this turn, instead tap it, remove it from combat, and heal all damage on it.)

Harbor Serpent

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
Harbor Serpent can't attack unless there are five or more Islands on the battlefield.

Time Ebb

Put target creature on top of its owner's library.

Swamp

Grave Peril

When a nonblack creature enters, sacrifice Grave Peril. If you do, destroy that creature.

Harrowing Journey

Target player draws three cards and loses 3 life.

Reality Ripple

Target artifact, creature, or land phases out. (While it's phased out, it's treated as though it doesn't exist. It phases in before its controller untaps during their next untap step.)

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.

Glimpse the Future

Look at the top three cards of your library. Put one of them into your hand and the rest into your graveyard.

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.

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.

Amass the Components

Draw three cards, then put a card from your hand on the bottom of your library.

Illusionary Armor

Enchant creature
Enchanted creature gets +4/+4.
When enchanted creature becomes the target of a spell or ability, sacrifice Illusionary Armor.

Assassin Initiate

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

Tandem Lookout

Soulbond (You may pair this creature with another unpaired creature when either enters. They remain paired for as long as you control both of them.)
As long as Tandem Lookout is paired with another creature, each of those creatures has "Whenever this creature deals damage to an opponent, draw a card."

Hideous Visage

Creatures you control gain intimidate until end of turn. (Each of those creatures can't be blocked except by artifact creatures and/or creatures that share a color with it.)

Destroy the Evidence

Destroy target land. Its controller reveals cards from the top of their library until they reveal a land card, then puts those cards into their graveyard.

Reckless Scholar

{T}: Target player draws a card, then discards a card.

Sleep

Tap all creatures target player controls. Those creatures don't untap during that player's next untap step.

Rise from the Grave

Put target creature card from a graveyard onto the battlefield under your control. That creature is a black Zombie in addition to its other colors and types.

Murder

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.

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.

Looter il-Kor

Shadow (This creature can block or be blocked by only creatures with shadow.)
Whenever Looter il-Kor deals damage to an opponent, draw a card, then discard a card.

Island

Submerged Boneyard

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

Mind Sludge

Target player discards a card for each Swamp you control.

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.)

Runewing

Stealer of Secrets

Whenever Stealer of Secrets deals combat damage to a player, draw a card.

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.

Doom Blade

Dispel

Hookblade Veteran

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

Dream Stalker

When Dream Stalker enters, return a permanent you control to its owner's hand.

Hired Blade

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

Brotherhood Patriarch

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

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.)

Defensive Stance

Enchant creature
Enchanted creature gets -1/+1.

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.

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.

Riptide Pilferer

Whenever Riptide Pilferer deals combat damage to a player, that player discards a card.
Morph {U} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)

Towering Viewpoint

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

Keymaster Rogue

Keymaster Rogue can't be blocked.
When Keymaster Rogue enters, return a creature you control to its owner's hand.

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.

Gryff Vanguard

Flying
When Gryff Vanguard enters, draw a card.

Dispersal Shield

Counter target spell if its mana value is less than or equal to the highest mana value among permanents you control.

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.)

Glimmerdust Nap

Enchant tapped creature
Enchanted creature doesn't untap during its controller's untap step.

Sensory Deprivation

Enchant creature
Enchanted creature gets -3/-0.

Acolyte of Xathrid

Assassin

Menace (This creature can't be blocked except by two or more creatures.)

Blade Juggler

Spectacle {2}{B} (You may cast this spell for its spectacle cost rather than its mana cost if an opponent lost life this turn.)
When Blade Juggler enters, it deals 1 damage to you and you draw a card.

Instill Infection

Put a -1/-1 counter on target creature.
Draw a card.

Maw of the Mire

Unsummon

Return target creature to its owner's hand.

Negate

Dream Thief

Flying
When Dream Thief enters, draw a card if you've cast another blue spell this turn.

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.

Remove

Cast this spell only during the declare attackers step and only if you've been attacked this step.
Return target attacking creature to its owner's hand.

Temporal Eddy

Put target creature or land on top of its owner's library.

Ragged Veins

Flash
Enchant creature
Whenever enchanted creature is dealt damage, its controller loses that much life.

Mind Rot

Sky-Eel School

Flying
When Sky-Eel School enters, draw a card, then discard a card.

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.)

Skygames

Enchant land
Enchanted land has "{T}: Target creature gains flying until end of turn. Activate only as a sorcery."