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

When Burglar Rat enters the battlefield, each opponent discards a card.

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

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 Ichor Rats enters the battlefield, each player gets a poison counter.

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.

Toxic 1 (Players dealt combat damage by this creature also get a poison counter.) Other Rats you control have toxic 1. When Karumonix enters the battlefield, 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.

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

When Lord Skitter's Butcher enters the battlefield, 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.

Whenever another Rat enters the battlefield under your control, 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."

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 Nashi, Moon Sage's Scion deals combat damage to a player, exile the top card of each player's library. Until end of turn, you may play one of those cards. If you cast a spell this way, pay life equal to its mana value rather than paying its mana cost.

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

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 Okiba-Gang Shinobi deals combat damage to a player, that player discards two cards.

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.

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.

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

When Rotting Rats enters the battlefield, 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.)

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

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.

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