Typhoid Rats

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

Harmonize

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.

Painful Lesson

Target player draws two cards and loses 2 life.

Diabolic Tutor

Search your library for a card, put that card into your hand, then shuffle.

Fell Stinger

Deathtouch
Exploit (When this creature enters, you may sacrifice a creature.)
When this creature exploits a creature, target player draws two cards and loses 2 life.

Haunted Mire

({T}: Add {B} or {G}.)
This land enters tapped.

Read the Bones

Scry 2, then draw two cards. You lose 2 life. (To scry 2, look at the top two cards of your library, then put any number of them on the bottom and the rest on top in any order.)

Forest

Arcane Signet

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

Foreboding Fruit

Target player draws two cards and loses 2 life.
Adamant — If at least three black mana was spent to cast this spell, create a Food token. (It's an artifact with "{2}, {T}, Sacrifice this token: You gain 3 life.")

Relentless Rats

This creature gets +1/+1 for each other creature on the battlefield named Relentless Rats.
A deck can have any number of cards named Relentless Rats.

Sultai Banner

{T}: Add {B}, {G}, or {U}.
{B}{G}{U}, {T}, Sacrifice this artifact: Draw a card.

Slitherbore Pathway

Darkbore Pathway

Darkbore Pathway // Slitherbore Pathway

Chromatic Lantern

Lands you control have "{T}: Add one mana of any color."
{T}: Add one mana of any color.

Decanter of Endless Water

You have no maximum hand size.
{T}: Add one mana of any color.

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.

Swamp

Cruel Tutor

Search your library for a card, then shuffle and put that card on top. You lose 2 life.

Mastermind's Acquisition

Choose one —
• Search your library for a card, put it into your hand, then shuffle.
• Put a card you own from outside the game into your hand.

Grim Tutor

Search your library for a card, put that card into your hand, then shuffle. You lose 3 life.

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.)

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."

Funeral Rites

You draw two cards, lose 2 life, then mill two cards.

Ashcoat of the Shadow Swarm

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.)

Zagoth Crystal

{T}: Add {B}, {G}, or {U}.
Cycling {2} ({2}, Discard this card: Draw a card.)

Infectious Inquiry

You draw two cards and you lose 2 life. Each opponent gets a poison counter.

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.

Tidechannel Pathway

Barkchannel Pathway

Barkchannel Pathway // Tidechannel Pathway

Murkwater Pathway

Clearwater Pathway

Clearwater Pathway // Murkwater Pathway

Ogre Slumlord

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

Mythos of Brokkos

If {U}{B} was spent to cast this spell, search your library for a card, put that card into your graveyard, then shuffle.
Return up to two permanent cards from your graveyard to your hand.

Sunken Hollow

({T}: Add {U} or {B}.)
This land enters tapped unless you control two or more basic lands.

Kodama's Reach

Field Research

Kicker {2}{U} (You may pay an additional {2}{U} as you cast this spell.)
Draw two cards. If this spell was kicked, draw three cards instead.

Island

Jace's Triumph

Draw two cards. If you control a Jace planeswalker, draw three cards instead.

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.

Commander's Sphere

{T}: Add one mana of any color in your commander's color identity.
Sacrifice this artifact: Draw a card.

Thrumming Stone

Spells you cast have ripple 4. (Whenever you cast a spell, you may reveal the top four cards of your library. You may cast spells with the same name as that spell from among the revealed cards without paying their mana costs. Put the rest on the bottom of your library.)