Until end of turn, whenever a player taps a Swamp for mana, that player adds an additional {B}.

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.

Target player reveals a number of cards from their hand equal to the number of Swamps you control. You choose one of them. That player discards that card.

Target player chooses a card in their hand and discards the rest.

Search target player's library for up to X cards, where X is the number of Swamps you control, and exile them. Then that player shuffles.

Whenever Ashcoat 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.)

This creature can't be blocked by Walls.

When this creature enters, each opponent discards a card.

Whenever this creature attacks or blocks, any player may exile a card from their graveyard. If a player does, this creature assigns no combat damage this turn.

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

When this creature enters, each player discards a card. Discard a card: Regenerate this creature.

Swampwalk (This creature can't be blocked as long as defending player controls a Swamp.) As long as this card is in your graveyard and you control a Swamp, creatures you control have swampwalk.

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

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

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

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.

{B}, Sacrifice a creature: Target player discards a card. Activate only as a sorcery.

Ninjutsu {3}{B} ({3}{B}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.) Whenever this creature deals combat damage to a player, that player discards two cards.

When this creature enters, it deals X damage to target creature or planeswalker an opponent controls, where X is the number of creature cards in your graveyard.

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.

Rat offering (You may cast this spell any time you could cast an instant by sacrificing a Rat and paying the difference in mana costs between this and the sacrificed Rat. Mana cost includes color.) Whenever a permanent is put into an opponent's graveyard, that player loses 1 life.

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.)

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.

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.)

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

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.

When this creature enters, target opponent discards a card.

When this creature enters, each player discards a card. Unearth {1}{B} ({1}{B}: Return this card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the next end step or if it would leave the battlefield. Unearth only as a sorcery.)

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.) Whenever this creature attacks, if defending player is poisoned, it gets +1/+1 until end of turn.

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

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

Ninjutsu {2}{B} ({2}{B}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.) Whenever this creature deals combat damage to a player, destroy target nonblack creature that player controls.

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

{B}, Sacrifice a creature: Destroy target nonblack creature.

Whenever a creature you control dies, you draw a card and you lose 1 life.

{B}, Pay 2 life: Draw a card.

As an additional cost to cast this spell, sacrifice a creature. Add {B}{B}{B}{B}.

Target creature gets -1/-1 until end of turn for each Swamp you control.

Until end of turn, lands you control gain "Sacrifice this land: Add {B}."