Arcane Signet

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

Nezumi Bone-Reader

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

Vampiric Tutor

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

Murder

Ashnod's Altar

Grave Pact

Whenever a creature you control dies, each other player sacrifices a creature of their choice.

Vampiric Rites

{1}{B}, Sacrifice a creature: You gain 1 life and draw a card.

Blightbelly Rat

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.)

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 Ichor Rats enters, each player gets a poison counter.

Cut Down

Destroy target creature with total power and toughness 5 or less.

Bad Moon

Swamp

Locust Miser

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

Pack Rat

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.

Thought Vessel

You have no maximum hand size.
{T}: Add {C}.

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.

Bog Rats

Black Market

Whenever a creature dies, put a charge counter on Black Market.
At the beginning of your first main phase, add {B} for each charge counter on Black Market.

Contamination

At the beginning of your upkeep, sacrifice Contamination unless you sacrifice a creature.
If a land is tapped for mana, it produces {B} instead of any other type and amount.

Jet Medallion

Black spells you cast cost {1} less to cast.

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.)

Relentless Rats

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

Gnat Miser

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

Reliquary Tower

Typhoid Rats

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

Eldrazi Monument

Creatures you control get +1/+1 and have flying and indestructible.
At the beginning of your upkeep, sacrifice a creature. If you can't, sacrifice Eldrazi Monument.

Mirror Box

The "legend rule" doesn't apply to permanents you control.
Each legendary creature you control gets +1/+1.
Each nontoken creature you control gets +1/+1 for each other creature you control with the same name as that creature.

Swarm of Rats

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

Demonic Tutor

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

Sol Ring

Grim Tutor

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

Heraldic Banner

As this artifact enters, choose a color.
Creatures you control of the chosen color get +1/+0.
{T}: Add one mana of the chosen color.

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.