Back for Seconds

Bargain (You may sacrifice an artifact, enchantment, or token as you cast this spell.)
Return up to two target creature cards from your graveyard to your hand. If this spell was bargained, you may put one of those cards with mana value 4 or less onto the battlefield instead of putting it into your hand.

Not Dead After All

Until end of turn, target creature you control gains "When this creature dies, return it to the battlefield tapped under its owner's control, then create a Wicked Role token attached to it." (Enchanted creature gets +1/+1. When this token is put into a graveyard, each opponent loses 1 life.)

Vraska's Fall

Each opponent sacrifices a creature or planeswalker of their choice and gets a poison counter.

Ravenous Rats

When this creature enters, target opponent discards a card.

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.

Mirkwood Bats

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

Furnace Skullbomb

{1}, Sacrifice this artifact: Draw a card.
{1}{R}, Sacrifice this artifact: Put two oil counters on target artifact or creature you control. Draw a card. Activate only as a sorcery.

Crypt Rats

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

Drown in Ichor

Target creature gets -4/-4 until end of turn. Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Lash of the Balrog

As an additional cost to cast this spell, sacrifice a creature or pay {4}.
Destroy target creature.

Bloodthorn Flail

Equipped creature gets +2/+1.
Equip—Pay {3} or discard a card.

Bonepicker Skirge

Flying
Corrupted — As long as an opponent has three or more poison counters, this creature has deathtouch and lifelink.

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."

Volt Charge

Volt Charge deals 3 damage to any target. Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

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."

Cairn Wanderer

Changeling (This card is every creature type.)
As long as a creature card with flying is in a graveyard, this creature has flying. The same is true for fear, first strike, double strike, deathtouch, haste, landwalk, lifelink, protection, reach, trample, shroud, and vigilance.

Mind Drain

Target opponent discards two cards, mills a card, and loses 1 life. You gain 1 life. (To mill a card, a player puts the top card of their library into their graveyard.)

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.

Blightbelly Rat

Toxic 1 (Players dealt combat damage by this creature also get a poison counter.)
When this creature dies, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Rummaging Goblin

Chittering Skitterling

Corrupted — Sacrifice an artifact or creature: Draw a card. Activate only if an opponent has three or more poison counters and only once each 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.

Swamp

Harried Spearguard

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

Leechridden Swamp

({T}: Add {B}.)
This land enters tapped.
{B}, {T}: Each opponent loses 1 life. Activate only if you control two or more black permanents.

Mad Ratter

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

Thundering Rebuke

Thundering Rebuke deals 4 damage to target creature or planeswalker.

Mountain

Swarm of Rats

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

The Autonomous Furnace

This land enters tapped.
{T}: Add {R}.
{1}{R}, {T}, Sacrifice this land: Draw a card.

Axiom Engraver

This creature enters with two oil counters on it.
{T}, Remove an oil counter from this creature, Discard a card: Draw a card.

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.