Rampant Growth

Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Counterspell

Mukotai Ambusher

Ninjutsu {1}{B} ({1}{B}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.)
Lifelink

Nezumi Ronin

Bushido 1 (Whenever this creature blocks or becomes blocked, it gets +1/+1 until end of turn.)

Nezumi Informant

When this creature enters, each opponent discards a card.

Diseased Vermin

Whenever this creature deals combat damage to a player, put an infection counter on it.
At the beginning of your upkeep, this creature deals X damage to target opponent previously dealt damage by it, where X is the number of infection counters on it.

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.

Dirty Wererat

{B}, Discard a card: Regenerate this creature.
Threshold — As long as there are seven or more cards in your graveyard, this creature gets +2/+2 and can't block.

Drainpipe Vermin

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

Beast Within

Destroy target permanent. Its controller creates a 3/3 green Beast creature token.

Burglar Rat

Cultivate

Search your library for up to two basic land cards, reveal those cards, put one onto the battlefield tapped and the other into your hand, then shuffle.

Yavimaya Coast

{T}: Add {C}.
{T}: Add {G} or {U}. This land deals 1 damage to you.

Crypt Rats

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

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.

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.

Nezumi Bladeblesser

This creature has deathtouch as long as you control an artifact.
This creature has menace as long as you control an enchantment. (It can't be blocked except by two or more creatures.)

Nashi, Moon Sage's Scion

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 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.

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.

Carrion Rats

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.

Arcane Signet

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

Command Tower

Chittering Rats

When this creature enters, target opponent puts a card from their hand on top of their library.

Ichor Rats

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.

Simic Growth Chamber

This land enters tapped.
When this land enters, return a land you control to its owner's hand.
{T}: Add {G}{U}.

Sidisi, Brood Tyrant

Whenever Sidisi enters or attacks, mill three cards.
Whenever one or more creature cards are put into your graveyard from your library, create a 2/2 black Zombie creature token.

Nezumi Shadow-Watcher

Sacrifice this creature: Destroy target Ninja.

Gutter Skulk

Nezumi Prowler

Ninjutsu {1}{B} ({1}{B}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.)
When this creature enters, target creature you control gains deathtouch and lifelink until end of turn.

Evolving Wilds

{T}, Sacrifice this land: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Earsplitting Rats

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

Simic Signet

Gnat Miser

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

Nashi, Moon's Legacy

Menace, ward {1}
Whenever Nashi attacks, exile up to one target legendary or Rat card from your graveyard and copy it. You may cast the copy. (You still pay its costs. A copy of a permanent spell becomes a token.)

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.)

Kodama's Reach

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.

Deathmask Nezumi

As long as you have seven or more cards in hand, this creature gets +2/+1 and has fear. (It can't be blocked except by artifact creatures and/or black creatures.)

Kuro's Taken

Bushido 1 (Whenever this creature blocks or becomes blocked, it gets +1/+1 until end of turn.)
{1}{B}: Regenerate this creature.

Ogre Slumlord

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

Nighteyes the Desecrator

{4}{B}: Put target creature card from a graveyard onto the battlefield under your control.

Nezumi Graverobber

{1}{B}: Exile target card from an opponent's graveyard. If no cards are in that graveyard, flip this creature.

Nezumi Graverobber // Nighteyes the Desecrator

Bog Rats

Disease Carriers

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

Muck Rats

Nezumi Cutthroat

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

Nezumi Bone-Reader

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

Farseek

Search your library for a Plains, Island, Swamp, or Mountain card, put it onto the battlefield tapped, then shuffle.

Okiba-Gang Shinobi

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.

Infected Vermin

{2}{B}: This creature deals 1 damage to each creature and each player.
Threshold — {3}{B}: This creature deals 3 damage to each creature and each player. Activate only if there are seven or more cards in your graveyard.