Sword of the Squeak

Equipped creature gets +1/+1 for each creature you control with base power or toughness 1.
Whenever a Hamster, Mouse, Rat, or Squirrel you control enters, you may attach this Equipment to that creature.
Equip {2}

Sol Ring

Harrowing Journey

Target player draws three cards and loses 3 life.

Ogre Slumlord

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

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 this creature.

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.

Twisted Sewer-Witch

When this creature enters, create a 1/1 black Rat creature token with "This creature can't block." Then for each Rat you control, create a Wicked Role token attached to that Rat. (If you control another Role on it, put that one into the graveyard. Enchanted creature gets +1/+1. When this token is put into a graveyard, each opponent loses 1 life.)

Abnormal Endurance

Until end of turn, target creature gets +2/+0 and gains "When this creature dies, return it to the battlefield tapped under its owner's control."

Engine Rat

Deathtouch
{5}{B}: Each opponent loses 2 life.

Lab Rats

Buyback {4} (You may pay an additional {4} as you cast this spell. If you do, put this card into your hand as it resolves.)
Create a 1/1 black Rat creature token.

Revenge of the Rats

Create a tapped 1/1 black Rat creature token for each creature card in your graveyard.
Flashback {2}{B}{B} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Drainpipe Vermin

When this creature dies, you may pay {B}. If you do, target player discards a card.

Succumb to Temptation

Sinuous Vermin

{3}{B}{B}: Monstrosity 3. (If this creature isn't monstrous, put three +1/+1 counters on it and it becomes monstrous.)
As long as this creature is monstrous, it has menace. (It can't be blocked except by two or more creatures.)

Arcane Signet

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

Gnat Miser

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

Fatal Push

Destroy target creature if it has mana value 2 or less.
Revolt — Destroy that creature if it has mana value 4 or less instead if a permanent left the battlefield under your control this turn.

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 token can't block."

Foul-Tongue Shriek

Target opponent loses 1 life for each attacking creature you control. You gain that much life.

Rat Colony

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

Devour Flesh

Target player sacrifices a creature of their choice, then gains life equal to that creature's toughness.

Pestilence Rats

Pestilence Rats's power is equal to the number of other Rats on the battlefield. (For example, as long as there are two other Rats on the battlefield, Pestilence Rats's power and toughness are 2/3.)

Deathmark

Bitter Revelation

Look at the top four cards of your library. Put two of them into your hand and the rest into your graveyard. You lose 2 life.

Rats' Feast

Exile X target cards from a single graveyard.

Psychic Whorl

Target opponent discards two cards. Then if you control a Rat, 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.)

Tangled Colony

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

Demon's Due

Scry 2, then draw two cards. You lose 2 life.

Ruin Rat

Deathtouch
When this creature dies, exile target card from an opponent's graveyard.

Swarmyard

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

Chittering Witch

When this creature 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.

Dark Bargain

Look at the top three cards of your library. Put two of them into your hand and the other into your graveyard. Dark Bargain deals 2 damage to you.

Ravenous Rats

When this creature enters, target opponent discards a card.

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.

Undercity Dire Rat

Rat Tail — When this creature dies, create a Treasure token. (It's an artifact with "{T}, Sacrifice this token: Add one mana of any color.")

Lord Skitter's Butcher

When this creature enters, choose one —
• Create a 1/1 black Rat creature token with "This token 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.

Fungal Fortitude

Flash
Enchant creature
Enchanted creature gets +2/+0.
When enchanted creature dies, return it to the battlefield tapped under its owner's control.

Mudflat Village

{T}: Add {C}.
{T}: Add {B}. Spend this mana only to cast a creature spell.
{1}{B}, {T}, Sacrifice this land: Return target Bat, Lizard, Rat, or Squirrel card from your graveyard to your hand.

Funeral Rites

You draw two cards, lose 2 life, then mill two cards.

Breathe Your Last

Destroy target creature or planeswalker. You gain 1 life for each of its colors.

Razortooth Rats

Fear (This creature can't be blocked except by artifact creatures and/or black creatures.)

Scrib Nibblers

{T}: Exile the top card of target player's library. If it's a land card, you gain 1 life.
Landfall — Whenever a land you control enters, you may untap this creature.

Contract Killing

Destroy target creature. Create two Treasure tokens. (They're artifacts with "{T}, Sacrifice this token: Add one mana of any color.")

Sewer Rats

{B}, Pay 1 life: This creature gets +1/+0 until end of turn. Activate no more than three times each turn.

Sword of the Meek

Equipped creature gets +1/+2.
Equip {2}
Whenever a 1/1 creature you control enters, you may return this card from your graveyard to the battlefield, then attach it to that creature.

Insatiable Frugivore

When this creature enters, create a Food token, then you may exile three cards from your graveyard. If you do, repeat this process.
{3}{B}, Sacrifice X Foods: Creatures you control get +X/+0 and gain menace until end of turn.

Atrocious Experiment

Target player mills two cards, draws two cards, and loses 2 life. (To mill a card, a player puts the top card of their library into their graveyard.)

Warehouse Tabby

Whenever an enchantment you control is put into a graveyard from the battlefield, create a 1/1 black Rat creature token with "This token can't block."
{1}{B}: This creature gains deathtouch until end of turn.

Village Rites

As an additional cost to cast this spell, sacrifice a creature.
Draw two cards.

Muck Rats

Wave of Rats

Trample
When this creature dies, if it dealt combat damage to a player this turn, return it to the battlefield under its owner's control.
Blitz {4}{B} (If you cast this spell for its blitz cost, it gains haste and "When this creature dies, draw a card." Sacrifice it at the beginning of the next end step.)

Heraldic Banner

As this artifact enters, choose a color.
Creatures you control of the chosen color get +1/+0.
{T}: Add one mana of the chosen color.

Armor of Shadows

Until end of turn, target creature gets +1/+0 and gains indestructible. (Damage and effects that say "destroy" don't destroy it.)

Gutter Skulk

Swamp

Voracious Vermin

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

Bone Shards

As an additional cost to cast this spell, sacrifice a creature or discard a card.
Destroy target creature or planeswalker.

Old Flitterfang

Flying
At the beginning of each end step, if a creature died this turn, create a Food token. (It's an artifact with "{2}, {T}, Sacrifice this token: You gain 3 life.")
{2}{B}, Sacrifice another creature or artifact: Old Flitterfang gets +2/+2 until end of turn.

Ratcatcher

Fear (This creature can't be blocked except by artifact creatures and/or black creatures.)
At the beginning of your upkeep, you may search your library for a Rat card, reveal it, put it into your hand, then shuffle.

Diresight

Surveil 2, then draw two cards. You lose 2 life. (To 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.)

Typhoid Rats

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

Crypt Rats

{X}: This creature deals X damage to each creature and each player. Spend only black mana on X.

Bog Rats

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.

Foreboding Fruit

Target player draws two cards and loses 2 life.
Adamant — If at least three black mana was spent to cast this spell, create a Food token. (It's an artifact with "{2}, {T}, Sacrifice this token: You gain 3 life.")

Witch's Cottage

({T}: Add {B}.)
This land enters tapped unless you control three or more other Swamps.
When this land enters untapped, you may put target creature card from your graveyard on top of your library.

Mirkwood Bats

Flying
Whenever you create or sacrifice a token, each opponent loses 1 life.

Innocuous Rat

When this creature dies, 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.)

Ruthless Radrat

Squad—Exile four cards from your graveyard. (As an additional cost to cast this spell, you may pay its squad cost any number of times. When this creature enters, create that many tokens that are copies of it.)
Menace (This creature can't be blocked except by two or more creatures.)

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 token can't block."