Solid

Deadly Rollick

If you control a commander, you may cast this spell without paying its mana cost.
Exile target creature.

Bojuka Bog

This land enters tapped.
When this land enters, exile target player's graveyard.
{T}: Add {B}.

Snuff Out

If you control a Swamp, you may pay 4 life rather than pay this spell's mana cost.
Destroy target nonblack creature. It can't be regenerated.

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.

Mortuary Mire

This land enters tapped.
When this land enters, you may put target creature card from your graveyard on top of your library.
{T}: Add {B}.

Sign in Blood

Target player draws two cards and loses 2 life.

Cabal Coffers

{2}, {T}: Add {B} for each Swamp you control.

Sketchy

Sol Ring

Bubbling Muck

Until end of turn, whenever a player taps a Swamp for mana, that player adds an additional {B}.

Dark Ritual

Extinction Event

Choose odd or even. Exile each creature with mana value of the chosen quality. (Zero is even.)

Echoing Return

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

Witch's Cottage

({T}: Add {B}.)
This land enters tapped unless you control three or more other Swamps.
When this land enters untapped, you may put target creature card from your graveyard on top of your library.

Feed the Swarm

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

Ogre Slumlord

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

Go for the Throat

Typhoid Rats

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

Mudflat Village

{T}: Add {C}.
{T}: Add {B}. Spend this mana only to cast a creature spell.
{1}{B}, {T}, Sacrifice this land: Return target Bat, Lizard, Rat, or Squirrel card from your graveyard to your hand.

Bad Moon

Ratcatcher

Fear (This creature can't be blocked except by artifact creatures and/or black creatures.)
At the beginning of your upkeep, you may search your library for a Rat card, reveal it, put it into your hand, then shuffle.

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.

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.

Defile

Target creature gets -1/-1 until end of turn for each Swamp you control.

Gray Merchant of Asphodel

When this creature 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.)

Eliminate

Destroy target creature or planeswalker with mana value 3 or less.

Throne of Eldraine

As Throne of Eldraine enters, choose a color.
{T}: Add four mana of the chosen color. Spend this mana only to cast monocolored spells of that color.
{3}, {T}: Draw two cards. Spend only mana of the chosen color to activate this ability.

Path of Ancestry

This land enters tapped.
{T}: Add one mana of any color in your commander's color identity. When that mana is spent to cast a creature spell that shares a creature type with your commander, scry 1. (Look at the top card of your library. You may put that card on the bottom.)

The Darkness Crystal

Black spells you cast cost {1} less to cast.
If a nontoken creature an opponent controls would die, instead exile it and you gain 2 life.
{4}{B}{B}, {T}: Put target creature card exiled with The Darkness Crystal onto the battlefield tapped under your control with two additional +1/+1 counters on it.

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.)

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 this creature.

Erebos, God of the Dead

Indestructible
As long as your devotion to black is less than five, Erebos isn't a creature. (Each {B} in the mana costs of permanents you control counts toward your devotion to black.)
Your opponents can't gain life.
{1}{B}, Pay 2 life: Draw a card.

Patchwork Banner

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

War Room

{T}: Add {C}.
{3}, {T}, Pay life equal to the number of colors in your commanders' color identity: Draw a card.

Skullclamp

Equipped creature gets +1/-1.
Whenever equipped creature dies, draw two cards.
Equip {1}

Bontu's Monument

Black creature spells you cast cost {1} less to cast.
Whenever you cast a creature spell, each opponent loses 1 life and you gain 1 life.

Cabal Stronghold

{T}: Add {C}.
{3}, {T}: Add {B} for each basic Swamp you control.

Swarmyard

{T}: Add {C}.
{T}: Regenerate target Insect, Rat, Spider, or Squirrel. (The next time it would be destroyed this turn, instead tap it, remove it from combat, and heal all damage on it.)

Valley Rotcaller

Menace
Whenever this creature attacks, each opponent loses X life and you gain X life, where X is the number of other Squirrels, Bats, Lizards, and Rats you control.

Phyrexian Arena

At the beginning of your upkeep, you draw a card and you lose 1 life.

Darkness

Prevent all combat damage that would be dealt this turn.

Proxy

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.)

Persistent Marshstalker

This creature gets +1/+0 for each other Rat you control.
Threshold — Whenever you attack with one or more Rats, if seven or more cards are in your graveyard, you may pay {2}{B}. If you do, return this card from your graveyard to the battlefield tapped and attacking.

Necropotence

Skip your draw step.
Whenever you discard a card, exile that card from your graveyard.
Pay 1 life: Exile the top card of your library face down. Put that card into your hand at the beginning of your next end step.

Black Market Connections

At the beginning of your first main phase, choose one or more —
• Sell Contraband — Create a Treasure token. You lose 1 life.
• Buy Information — Draw a card. You lose 2 life.
• Hire a Mercenary — Create a 3/2 colorless Shapeshifter creature token with changeling. You lose 3 life. (It is every creature type.)

Doom Blade

Archenemy's Charm

Choose one —
• Exile target creature or planeswalker.
• Return one or two target creature and/or planeswalker cards from your graveyard to your hand.
• Put two +1/+1 counters on target creature you control. It gains lifelink until end of turn.

Nightmare

Flying (This creature can't be blocked except by creatures with flying or reach.)
Nightmare's power and toughness are each equal to the number of Swamps you control.

Saw in Half

Destroy target creature. If that creature dies this way, its controller creates two tokens that are copies of that creature, except their power is half that creature's power and their toughness is half that creature's toughness. Round up each time.

Castle Locthwain

This land enters tapped unless you control a Swamp.
{T}: Add {B}.
{1}{B}{B}, {T}: Draw a card, then you lose life equal to the number of cards in your hand.

Swamp

Cover of Darkness

As this enchantment enters, choose a creature type.
Creatures of the chosen type have fear. (They can't be blocked except by artifact creatures and/or black creatures.)

Jet Medallion

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

Lord Skitter, Sewer King

Whenever another Rat you control enters, 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 token can't block."

Rat Colony

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

Barren Moor

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

Sword of the Squeak

Equipped creature gets +1/+1 for each creature you control with base power or toughness 1.
Whenever a Hamster, Mouse, Rat, or Squirrel you control enters, you may attach this Equipment to that creature.
Equip {2}

Endless Atlas

{2}, {T}: Draw a card. Activate only if you control three or more lands with the same name.

Grave Pact

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