Plague of Vermin

Starting with you, each player may pay any amount of life. Repeat this process until no one pays life. Each player creates a 1/1 black Rat creature token for each 1 life they paid this way.

Lord Skitter's Butcher

When Lord Skitter's Butcher enters, choose one —
• Create a 1/1 black Rat creature token with "This creature can't block."
• You may sacrifice another creature. If you do, scry 2, then draw a card.
• Creatures you control gain menace until end of turn.

Lord Skitter, Sewer King

Whenever another Rat you control enters, exile up to one target card from an opponent's graveyard.
At the beginning of combat on your turn, create a 1/1 black Rat creature token with "This creature can't block."

Mistvault Bridge

Mistvault Bridge enters tapped.
Indestructible
{T}: Add {U} or {B}.

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.)

Forge Boss

Whenever you sacrifice one or more other creatures, Forge Boss deals 2 damage to each opponent. This ability triggers only once each turn.

Oversold Cemetery

At the beginning of your upkeep, if you have four or more creature cards in your graveyard, you may return target creature card from your graveyard to your hand.

Command Tower

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

Rat Colony

Rat Colony gets +1/+0 for each other Rat you control.
A deck can have any number of cards named Rat Colony.

Refurbished Familiar

Affinity for artifacts (This spell costs {1} less to cast for each artifact you control.)
Flying
When Refurbished Familiar enters, each opponent discards a card. For each opponent who can't, you draw a card.

Counterspell

Nezumi Informant

When Nezumi Informant enters, each opponent discards a card.

Gnat Miser

Each opponent's maximum hand size is reduced by one.

Maskwood Nexus

Creatures you control are every creature type. The same is true for creature spells you control and creature cards you own that aren't on the battlefield.
{3}, {T}: Create a 2/2 blue Shapeshifter creature token with changeling. (It is every creature type.)

Valley Rotcaller

Menace
Whenever Valley Rotcaller attacks, each opponent loses X life and you gain X life, where X is the number of other Squirrels, Bats, Lizards, and Rats you control.

Thought Vessel

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

Stronghold Rats

Shadow (This creature can block or be blocked by only creatures with shadow.)
Whenever Stronghold Rats deals combat damage to a player, each player discards a card.

Butcher of Malakir

Flying
Whenever Butcher of Malakir or another creature you control dies, each opponent sacrifices a creature.

Cabal Coffers

{2}, {T}: Add {B} for each Swamp you control.

Chittering Witch

When Chittering Witch enters, create a number of 1/1 black Rat creature tokens equal to the number of opponents you have.
{1}{B}, Sacrifice a creature: Target creature gets -2/-2 until end of turn.

Juri, Master of the Revue

Whenever you sacrifice a permanent, put a +1/+1 counter on Juri, Master of the Revue.
When Juri dies, it deals damage equal to its power to any target.

Soured Springs

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

Reanimate

Put target creature card from a graveyard onto the battlefield under your control. You lose life equal to its mana value.

Relic of Sauron

{T}: Add two mana in any combination of {U}, {B}, and/or {R}.
{3}, {T}: Draw two cards, then discard a card.

Distant Melody

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

Tragic Slip

Target creature gets -1/-1 until end of turn.
Morbid — That creature gets -13/-13 until end of turn instead if a creature died this turn.

Bloodfell Caves

Bloodfell Caves enters tapped.
When Bloodfell Caves enters, you gain 1 life.
{T}: Add {B} or {R}.

Island

Bedevil

Destroy target artifact, creature, or planeswalker.

Coat of Arms

Each creature gets +1/+1 for each other creature on the battlefield that shares at least one creature type with it. (For example, if two Goblin Warriors and a Goblin Shaman are on the battlefield, each gets +2/+2.)

Mountain

Wick, the Whorled Mind

Whenever Wick or another Rat you control enters, create a 1/1 black Snail creature token if you don't control a Snail. Otherwise, put a +1/+1 counter on a Snail you control.
{U}{B}{R}, Sacrifice a Snail: Wick deals damage equal to the sacrificed creature's power to each opponent. Then draw cards equal to the sacrificed creature's power.

Tangled Colony

Tangled Colony can't block.
When Tangled Colony dies, create X 1/1 black Rat creature tokens with "This creature can't block," where X is the amount of damage dealt to it this turn.

Chromatic Lantern

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

Bloodline Pretender

Changeling (This card is every creature type.)
As Bloodline Pretender enters, choose a creature type.
Whenever another creature you control of the chosen type enters, put a +1/+1 counter on Bloodline Pretender.

Piper of the Swarm

Rats you control have menace.
{1}{B}, {T}: Create a 1/1 black Rat creature token.
{2}{B}{B}, {T}, Sacrifice three Rats: Gain control of target creature.

Ashcoat of the Shadow Swarm

Whenever Ashcoat of the Shadow Swarm attacks or blocks, other Rats you control get +X/+X until end of turn, where X is the number of Rats you control.
At the beginning of your end step, you may mill four cards. If you do, return up to two Rat creature cards from your graveyard to your hand. (To mill a card, put the top card of your library into your graveyard.)

Sol Ring

Patchwork Banner

As Patchwork Banner enters, choose a creature type.
Creatures you control of the chosen type get +1/+1.
{T}: Add one mana of any color.

Marrow-Gnawer

All Rats have fear.
{T}, Sacrifice a Rat: Create X 1/1 black Rat creature tokens, where X is the number of Rats you control.

Totentanz, Swarm Piper

Whenever Totentanz, Swarm Piper or another nontoken creature you control dies, create a 1/1 black Rat creature token with "This creature can't block."
{1}{B}: Target attacking Rat you control gains deathtouch until end of turn.

Jagged Barrens

Jagged Barrens enters tapped.
When Jagged Barrens enters, it deals 1 damage to target opponent.
{T}: Add {B} or {R}.

Kindred Charge

Choose a creature type. For each creature you control of the chosen type, create a token that's a copy of that creature. Those tokens gain haste. Exile them at the beginning of the next end step.

Reliquary Tower

Voracious Vermin

When Voracious Vermin enters, create a 1/1 black Rat creature token with "This creature can't block."
Whenever another creature you control dies, put a +1/+1 counter on Voracious Vermin.

Ogre Chitterlord

Menace
Whenever Ogre Chitterlord enters or attacks, create two 1/1 black Rat creature tokens with "This creature can't block." Then if you control five or more Rats, each Rat you control gets +2/+0 until end of turn.

Ruthless Deathfang

Flying
Whenever you sacrifice a creature, target opponent sacrifices a creature.

Toxrill, the Corrosive

At the beginning of each end step, put a slime counter on each creature you don't control.
Creatures you don't control get -1/-1 for each slime counter on them.
Whenever a creature you don't control with a slime counter on it dies, create a 1/1 black Slug creature token.
{U}{B}, Sacrifice a Slug: Draw a card.

Black Market

Whenever a creature dies, put a charge counter on Black Market.
At the beginning of your first main phase, add {B} for each charge counter on Black Market.

Silverbluff Bridge

Silverbluff Bridge enters tapped.
Indestructible
{T}: Add {U} or {R}.

Ichor Rats

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
When Ichor Rats enters, each player gets a poison counter.

Swarmyard Massacre

Create two 1/1 green Squirrel creature tokens. Then each creature that isn't an Insect, Rat, Spider, or Squirrel gets -1/-1 until end of turn for each creature you control that's an Insect, Rat, Spider, or Squirrel.

Haunted Ridge

Haunted Ridge enters tapped unless you control two or more other lands.
{T}: Add {B} or {R}.

Swamp

Rakdos Carnarium

Rakdos Carnarium enters tapped.
When Rakdos Carnarium enters, return a land you control to its owner's hand.
{T}: Add {B}{R}.

Ogre Slumlord

Whenever another nontoken creature dies, you may create a 1/1 black Rat creature token.
Rats you control have deathtouch.

Vren, the Relentless

Ward {2}
If a creature an opponent controls would die, exile it instead.
At the beginning of each end step, create X 1/1 black Rat creature tokens with "This creature gets +1/+1 for each other Rat you control," where X is the number of creatures your opponents controlled that were exiled this turn.

Locust Miser

Each opponent's maximum hand size is reduced by two.

Roaming Throne

Ward {2}
As Roaming Throne enters, choose a creature type.
Roaming Throne is the chosen type in addition to its other types.
If a triggered ability of another creature you control of the chosen type triggers, it triggers an additional time.

Decanter of Endless Water

You have no maximum hand size.
{T}: Add one mana of any color.

Leyline of Transformation

If Leyline of Transformation is in your opening hand, you may begin the game with it on the battlefield.
As Leyline of Transformation 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.

Rat Out

Up to one target creature gets -1/-1 until end of turn. You create a 1/1 black Rat creature token with "This creature can't block."

Xenograft

As Xenograft enters, choose a creature type.
Each creature you control is the chosen type in addition to its other types.

Skullcap Snail

When Skullcap Snail enters, target opponent exiles a card from their hand.

Drowned Catacomb

Drowned Catacomb enters tapped unless you control an Island or a Swamp.
{T}: Add {U} or {B}.

Dimir Aqueduct

Dimir Aqueduct enters tapped.
When Dimir Aqueduct enters, return a land you control to its owner's hand.
{T}: Add {U}{B}.

Ink-Eyes, Servant of Oni

Ninjutsu {3}{B}{B} ({3}{B}{B}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.)
Whenever Ink-Eyes, Servant of Oni deals combat damage to a player, you may put target creature card from that player's graveyard onto the battlefield under your control.
{1}{B}: Regenerate Ink-Eyes.

Song of Totentanz

Create X 1/1 black Rat creature tokens with "This creature can't block." Creatures you control gain haste until end of turn.

Pitiless Plunderer

Whenever another creature you control dies, create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Ayara, First of Locthwain

Whenever Ayara, First of Locthwain or another black creature you control enters, each opponent loses 1 life and you gain 1 life.
{T}, Sacrifice another black creature: Draw a card.

Vat Emergence

Put target creature card from a graveyard onto the battlefield under your control. Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Impact Tremors

Whenever a creature you control enters, Impact Tremors deals 1 damage to each opponent.

Pack Rat

Pack Rat's power and toughness are each equal to the number of Rats you control.
{2}{B}, Discard a card: Create a token that's a copy of Pack Rat.

Ashad, the Lone Cyberman

The first nonlegendary artifact spell you cast each turn has casualty 2. (As you cast it, you may sacrifice a creature with power 2 or greater. When you do, copy it. A copy of an artifact spell becomes a token.)
Whenever you sacrifice another creature, put a +1/+1 counter on Ashad, the Lone Cyberman.

Toxic Deluge

As an additional cost to cast this spell, pay X life.
All creatures get -X/-X until end of turn.

Swarmyard

{T}: Add {C}.
{T}: Regenerate target Insect, Rat, Spider, or Squirrel. (The next time it would be destroyed, instead tap it, remove it from combat, and heal all damage on it.)

Burglar Rat

When Burglar Rat enters, each opponent discards a card.

Prowling Geistcatcher

Whenever you sacrifice another creature, exile it. If that creature was a token, put a +1/+1 counter on Prowling Geistcatcher.
When Prowling Geistcatcher leaves the battlefield, return each card exiled with it to the battlefield under your control.

Terramorphic Expanse

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

Gloomlake Verge

{T}: Add {U}.
{T}: Add {B}. Activate only if you control an Island or a Swamp.

Karumonix, the Rat King

Toxic 1 (Players dealt combat damage by this creature also get a poison counter.)
Other Rats you control have toxic 1.
When Karumonix enters, look at the top five cards of your library. You may reveal any number of Rat cards from among them and put the revealed cards into your hand. Put the rest on the bottom of your library in a random order.

Mad Ratter

Whenever you draw your second card each turn, create two 1/1 black Rat creature tokens.

Akoum Refuge

Akoum Refuge enters tapped.
When Akoum Refuge enters, you gain 1 life.
{T}: Add {B} or {R}.

The Ozolith

Whenever a creature you control leaves the battlefield, if it had counters on it, put those counters on The Ozolith.
At the beginning of combat on your turn, if The Ozolith has counters on it, you may move all counters from The Ozolith onto target creature.