Corrupted Conviction

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

Sanity Gnawers

When this creature enters, target player discards a card at random.

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.

Rancid Rats

Skulk (This creature can't be blocked by creatures with greater power.)
Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)

Nezumi Cutthroat

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

Blackcleave Cliffs

This land enters tapped unless you control two or fewer other lands.
{T}: Add {B} or {R}.

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.

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.

Ogre Chitterlord

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

Replicating Ring

{T}: Add one mana of any color.
At the beginning of your upkeep, put a night counter on this artifact. Then if it has eight or more night counters on it, remove all of them and create eight colorless snow artifact tokens named Replicated Ring with "{T}: Add one mana of any color."

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."

Go for the Throat

Disease Carriers

When this creature dies, target creature gets -2/-2 until end of turn.

Raid Bombardment

Whenever a creature you control with power 2 or less attacks, this enchantment deals 1 damage to the player or planeswalker that creature is attacking.

Burglar Rat

When this creature enters, each opponent discards a card.

Song of Totentanz

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

Bone Shards

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

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.)

Witchstalker Frenzy

This spell costs {1} less to cast for each creature that attacked this turn.
Witchstalker Frenzy deals 5 damage to target creature.

Tattered Ratter

Whenever a Rat you control becomes blocked, it gets +2/+0 until end of turn.

Gnawing Vermin

When this creature enters, target player mills two cards.
When this creature dies, target creature you don't control gets -1/-1 until end of turn.

Ruin Rat

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

Swarm of Rats

Swarm of Rats's power is equal to the number of Rats you control.

Lord Skitter's Blessing

When this enchantment enters, create a Wicked Role token attached to target creature you control. (Enchanted creature gets +1/+1. When this token is put into a graveyard, each opponent loses 1 life.)
At the beginning of your draw step, if you control an enchanted creature, you lose 1 life and you draw an additional card.

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."

Pyre of Heroes

{2}, {T}, Sacrifice a creature: Search your library for a creature card that shares a creature type with the sacrificed creature and has mana value equal to 1 plus that creature's mana value. Put that card onto the battlefield, then shuffle. Activate only as a sorcery.

Swamp

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.)

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.

Totentanz, Swarm Piper

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

Juri, Master of the Revue

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

Shared Animosity

Whenever a creature you control attacks, it gets +1/+0 until end of turn for each other attacking creature that shares a creature type with it.

Garna, Bloodfist of Keld

Whenever another creature you control dies, draw a card if it was attacking. Otherwise, Garna deals 1 damage to each opponent.

Crippling Fear

Choose a creature type. Creatures that aren't of the chosen type get -3/-3 until end of turn.

Vanquisher's Banner

As this artifact enters, choose a creature type.
Creatures you control of the chosen type get +1/+1.
Whenever you cast a creature spell of the chosen type, draw a card.

Eaten Alive

As an additional cost to cast this spell, sacrifice a creature or pay {3}{B}.
Exile target creature or planeswalker.

Impact Tremors

Whenever a creature you control enters, this enchantment deals 1 damage to each opponent.

Village Rites

Rat Colony

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

Pest Problem

Create two 1/1 black Rat creature tokens with "This token can't block." (Then exile this card. You may cast the creature later from exile.)

Ratcatcher Trainee

During your turn, this creature has first strike.

Ratcatcher Trainee // Pest Problem

Redcap Gutter-Dweller

Menace
When this creature enters, create two 1/1 black Rat creature tokens with "This token can't block."
At the beginning of your upkeep, you may sacrifice another creature. If you do, put a +1/+1 counter on this creature and exile the top card of your library. You may play that card this turn.

Mountain

Gnawing Crescendo

Creatures you control get +2/+0 until end of turn. Whenever a nontoken creature you control dies this turn, create a 1/1 black Rat creature token with "This token can't block."

Sol Ring

Ravenous Rats

When this creature enters, target opponent discards a card.

Ogre Slumlord

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

Mayhem Devil

Whenever a player sacrifices a permanent, this creature deals 1 damage to any target.

Crypt Rats

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

Harried Spearguard

Haste
When this creature dies, create a 1/1 black Rat creature token with "This token can't block."

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.

Final Flourish

Kicker—Sacrifice an artifact or creature. (You may sacrifice an artifact or creature in addition to any other costs as you cast this spell.)
Target creature gets -2/-2 until end of turn. If this spell was kicked, that creature gets -6/-6 until end of turn instead.

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.)

Hellhole Rats

Haste
When this creature enters, target player discards a card. This creature deals damage to that player equal to that card's mana value.

Charging Hooligan

Whenever this creature attacks, it gets +1/+0 until end of turn for each attacking creature. If a Rat is attacking, this creature gains trample until end of turn.

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.)

Drainpipe Vermin

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

Typhoid Rats

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

Mad Ratter

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

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.

Necrosynthesis

Enchant creature
Enchanted creature has "Whenever another creature dies, put a +1/+1 counter on this creature."
When enchanted creature dies, look at the top X cards of your library, where X is its power. Put one of those cards into your hand and the rest on the bottom of your library in a random order.

Eliminate

Destroy target creature or planeswalker with mana value 3 or less.

Graf Rats

At the beginning of combat on your turn, if you both own and control this creature and a creature named Midnight Scavengers, exile them, then meld them into Chittering Host.

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.

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.

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.

Midnight Scavengers

When this creature enters, you may return target creature card with mana value 3 or less from your graveyard to your hand.
(Melds with Graf Rats.)

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.

Edgewall Pack

Menace (This creature can't be blocked except by two or more creatures.)
When this creature enters, create a 1/1 black Rat creature token with "This token can't block."