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.

Cast Down

Crypt Rats

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

Fake Your Own Death

Until end of turn, target creature gets +2/+0 and gains "When this creature dies, return it to the battlefield tapped under its owner's control and you create a Treasure token." (It's an artifact with "{T}, Sacrifice this token: Add one mana of any color.")

Funeral Rites

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

Witch's Cottage

({T}: Add {B}.)
Witch's Cottage enters tapped unless you control three or more other Swamps.
When Witch's Cottage enters untapped, you may put target creature card from your graveyard on top of your library.

Undercity Scrounger

{T}: Create a Treasure token. Activate only if a creature died this turn. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

The Dross Pits

The Dross Pits enters tapped.
{T}: Add {B}.
{1}{B}, {T}, Sacrifice The Dross Pits: Draw a card.

Kaya's Ghostform

Enchant creature or planeswalker you control
When enchanted permanent dies or is put into exile, return that card to the battlefield under your control.

Wayfarer's Bauble

{2}, {T}, Sacrifice Wayfarer's Bauble: Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Arcane Signet

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

Viscera Seer

Sacrifice a creature: Scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Fog of Gnats

Unearth

Return target creature card with mana value 3 or less from your graveyard to the battlefield.
Cycling {2} ({2}, Discard this card: Draw a card.)

Carrion Feeder

Carrion Feeder can't block.
Sacrifice a creature: Put a +1/+1 counter on Carrion Feeder.

Night's Whisper

Gray Merchant of Asphodel

When Gray Merchant of Asphodel enters, each opponent loses X life, where X is your devotion to black. You gain life equal to the life lost this way. (Each {B} in the mana costs of permanents you control counts toward your devotion to black.)

Feed the Swarm

Destroy target creature or enchantment an opponent controls. You lose life equal to that permanent's mana value.

Pestilence

At the beginning of the end step, if no creatures are on the battlefield, sacrifice Pestilence.
{B}: Pestilence deals 1 damage to each creature and each player.

Raise the Draugr

Choose one —
• Return target creature card from your graveyard to your hand.
• Return two target creature cards that share a creature type from your graveyard to your hand.

Feign Death

Until end of turn, target creature gains "When this creature dies, return it to the battlefield tapped under its owner's control with a +1/+1 counter on it."

Star Compass

Star Compass enters tapped.
{T}: Add one mana of any color that a basic land you control could produce.

Ornithopter of Paradise

Charcoal Diamond

Charcoal Diamond enters tapped.
{T}: Add {B}.

Pointed Discussion

You draw two cards, lose 2 life, then create a Blood token. (It's an artifact with "{1}, {T}, Discard a card, Sacrifice this artifact: Draw a card.")

Devouring Swarm

Flying
Sacrifice a creature: Devouring Swarm gets +1/+1 until end of turn.

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

Skullsnatcher

Ninjutsu {B} ({B}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.)
Whenever Skullsnatcher deals combat damage to a player, exile up to two target cards from that player's graveyard.

Undying Malice

Bonder's Ornament

{T}: Add one mana of any color.
{4}, {T}: Each player who controls a permanent named Bonder's Ornament draws a card.

Bojuka Bog

Bojuka Bog enters tapped.
When Bojuka Bog enters, exile target player's graveyard.
{T}: Add {B}.

Village Rites

As an additional cost to cast this spell, sacrifice a creature.
Draw two cards.

Annihilating Glare

As an additional cost to cast this spell, pay {4} or sacrifice an artifact or creature.
Destroy target creature or planeswalker.

Deadly Dispute

As an additional cost to cast this spell, sacrifice an artifact or creature.
Draw two cards and create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Eyeblight Massacre

Non-Elf creatures get -2/-2 until end of turn.

Echoing Return

Return target creature card and all other cards with the same name as that card from your graveyard to your hand.

Funeral March

Enchant creature
When enchanted creature leaves the battlefield, its controller sacrifices a creature of their choice.

Barren Moor

Barren Moor enters tapped.
{T}: Add {B}.
Cycling {B} ({B}, Discard this card: Draw a card.)

Go for the Throat

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.)

Executioner's Capsule

{1}{B}, {T}, Sacrifice Executioner's Capsule: Destroy target nonblack creature.

Azra Smokeshaper

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 Azra Smokeshaper enters, target creature you control gains indestructible until end of turn.

Swamp

Crystal Grotto

When Crystal Grotto enters, scry 1.
{T}: Add {C}.
{1}, {T}: Add one mana of any color.

Dark Ritual

Return from Extinction

Costly Plunder

As an additional cost to cast this spell, sacrifice an artifact or creature.
Draw two cards.

Bone Shards

As an additional cost to cast this spell, sacrifice a creature or discard a card.
Destroy target creature or planeswalker.

Reckoner's Bargain

As an additional cost to cast this spell, sacrifice an artifact or creature.
You gain life equal to the sacrificed permanent's mana value. Draw two cards.

Seal of Doom

Sacrifice Seal of Doom: Destroy target nonblack creature. It can't be regenerated.