Butcher of Malakir

Flying
Whenever this creature or another creature you control dies, each opponent sacrifices a creature of their choice.

Typhoid Rats

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

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.

Swamp

Crypt Rats

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

Temple of Aclazotz

(Transforms from Arguel's Blood Fast.)
{T}: Add {B}.
{T}, Sacrifice a creature: You gain life equal to the sacrificed creature's toughness.

Arguel's Blood Fast

{1}{B}, Pay 2 life: Draw a card.
At the beginning of your upkeep, if you have 5 or less life, you may transform Arguel's Blood Fast.

Arguel's Blood Fast // Temple of Aclazotz

Dark Prophecy

Whenever a creature you control dies, you draw a card and you lose 1 life.

Rogue's Passage

{T}: Add {C}.
{4}, {T}: Target creature can't be blocked this turn.

Cloak and Dagger

Equipped creature gets +2/+0 and has shroud. (It can't be the target of spells or abilities.)
Whenever a Rogue creature enters, you may attach this Equipment to it.
Equip {3}

Dread Cacodemon

When this creature enters, if you cast it from your hand, destroy all creatures your opponents control, then tap all other creatures you control.

Tragic Slip

Target creature gets -1/-1 until end of turn.
Morbid — That creature gets -13/-13 until end of turn instead if a creature died this turn.

Dictate of Erebos

Flash
Whenever a creature you control dies, each opponent sacrifices a creature of their choice.

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.)

Will-o'-the-Wisp

Flying (This creature can't be blocked except by creatures with flying or reach.)
{B}: Regenerate this creature. (The next time this creature would be destroyed this turn, instead tap it, remove it from combat, and heal all damage on it.)

Terramorphic Expanse

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

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.)

Secret Salvage

Exile target nonland card from your graveyard. Search your library for any number of cards with the same name as that card, reveal them, put them into your hand, then shuffle.

Feaster of Fools

Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for {1} or one mana of that creature's color.)
Flying
Devour 2 (As this creature enters, you may sacrifice any number of creatures. It enters with twice that many +1/+1 counters on it.)

Thousand-Year Elixir

You may activate abilities of creatures you control as though those creatures had haste.
{1}, {T}: Untap target creature.

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.)

Sinuous Vermin

{3}{B}{B}: Monstrosity 3. (If this creature isn't monstrous, put three +1/+1 counters on it and it becomes monstrous.)
As long as this creature is monstrous, it has menace. (It can't be blocked except by two or more creatures.)

Foul-Tongue Shriek

Target opponent loses 1 life for each attacking creature you control. You gain that much life.

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.)

Myriad Landscape

This land enters tapped.
{T}: Add {C}.
{2}, {T}, Sacrifice this land: Search your library for up to two basic land cards that share a land type, put them onto the battlefield tapped, then shuffle.

Altar of the Brood

Whenever another permanent you control enters, each opponent mills a card.

Ink-Eyes, Servant of Oni

Ninjutsu {3}{B}{B} ({3}{B}{B}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.)
Whenever Ink-Eyes deals combat damage to a player, you may put target creature card from that player's graveyard onto the battlefield under your control.
{1}{B}: Regenerate Ink-Eyes.

Gruesome Fate

Each opponent loses 1 life for each creature you control.

Coat of Arms

Each creature gets +1/+1 for each other creature on the battlefield that shares at least one creature type with it. (For example, if two Goblin Warriors and a Goblin Shaman are on the battlefield, each gets +2/+2.)

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.

Swarm of Rats

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

Magewright's Stone

{1}, {T}: Untap target creature that has an activated ability with {T} in its cost.

Bad Moon

Chittering Rats

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

Infernal Tribute

{2}, Sacrifice a nontoken permanent: Draw a card.

Horror of Horrors

Sacrifice a Swamp: Regenerate target black creature. (The next time that creature would be destroyed this turn, instead tap it, remove it from combat, and heal all damage on it.)

Sol Ring

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.

Ransack the Lab

Look at the top three cards of your library. Put one of them into your hand and the rest into your graveyard.

Dark Ritual

Rat Colony

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

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.

Shield of the Avatar

If a source would deal damage to equipped creature, prevent X of that damage, where X is the number of creatures you control.
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

Bone Splinters

As an additional cost to cast this spell, sacrifice a creature.
Destroy target creature.

Sign in Blood

Target player draws two cards and loses 2 life.

Pestilence Rats

Pestilence Rats's power is equal to the number of other Rats on the battlefield. (For example, as long as there are two other Rats on the battlefield, Pestilence Rats's power and toughness are 2/3.)

Diabolic Tutor

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

Mutilate

All creatures get -1/-1 until end of turn for each Swamp you control.

Blood Artist

Whenever this creature or another creature dies, target player loses 1 life and you gain 1 life.

Bojuka Bog

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

Phyrexian Tower

{T}: Add {C}.
{T}, Sacrifice a creature: Add {B}{B}.

Evolving Wilds

Lab Rats

Buyback {4} (You may pay an additional {4} as you cast this spell. If you do, put this card into your hand as it resolves.)
Create a 1/1 black Rat creature token.

Defile

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

Beseech the Queen

({2/B} can be paid with any two mana or with {B}. This card's mana value is 6.)
Search your library for a card with mana value less than or equal to the number of lands you control, reveal it, put it into your hand, then shuffle.

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.

Ashnod's Altar

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.