Vraska's Fall

Each opponent sacrifices a creature or planeswalker of their choice and gets a poison counter.

Toxic Nim

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
{B}: Regenerate Toxic Nim.

Defile

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

Contagious Nim

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)

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.

Howl from Beyond

Target creature gets +X/+0 until end of turn.

Crypt Rats

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

Rancid Rats

Skulk (This creature can't be blocked by creatures with greater power.)
Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)

Barren Moor

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

Phyresis

Enchant creature
Enchanted creature has infect. (It deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)

Sugar Rush

Target creature gets +3/+0 until end of turn.
Draw a card.

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 Sinuous Vermin is monstrous, it has menace. (It can't be blocked except by two or more creatures.)

Quag Sickness

Enchant creature
Enchanted creature gets -1/-1 for each Swamp you control.

Dross Skullbomb

{1}, Sacrifice Dross Skullbomb: Draw a card.
{2}{B}, Sacrifice Dross Skullbomb: Return target creature card from your graveyard to your hand. Draw a card. Activate only as a sorcery.

Hopeless Nightmare

When Hopeless Nightmare enters, each opponent discards a card and loses 2 life.
When Hopeless Nightmare is put into a graveyard from the battlefield, scry 2.
{2}{B}: Sacrifice Hopeless Nightmare.

Ichorclaw Myr

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
Whenever Ichorclaw Myr becomes blocked, it gets +2/+2 until end of turn.

Corpse Cur

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
When Corpse Cur enters, you may return target creature card with infect from your graveyard to your hand.

Changeling Outcast

Changeling (This card is every creature type.)
Changeling Outcast can't block and can't be blocked.

Virulent Wound

Put a -1/-1 counter on target creature. When that creature dies this turn, its controller gets a poison counter.

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.

Burglar Rat

When this creature enters, each opponent discards a card.

Dark Ritual

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.)

Night's Whisper

Syphon Mind

Each other player discards a card. You draw a card for each card discarded this way.

Consume Spirit

Spend only black mana on X.
Consume Spirit deals X damage to any target and you gain X life.

Thieves' Tools

When Thieves' Tools enters, create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")
Equipped creature can't be blocked as long as its power is 3 or less.
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

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.

Urborg Uprising

Return up to two target creature cards from your graveyard to your hand.
Draw a card.

Tainted Strike

Target creature gets +1/+0 and gains infect until end of turn. (It deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)

Spread the Sickness

Destroy target creature, then proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Rat Colony

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

Plague Stinger

Flying
Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)

Grim Affliction

Put a -1/-1 counter on target creature, then proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Nihil Spellbomb

{T}, Sacrifice Nihil Spellbomb: Exile target player's graveyard.
When Nihil Spellbomb is put into a graveyard from the battlefield, you may pay {B}. If you do, draw a card.

Voracious Vermin

When Voracious Vermin enters, create a 1/1 black Rat creature token with "This creature can't block."
Whenever another creature you control dies, put a +1/+1 counter on Voracious Vermin.

Phyrexian Digester

Blackcleave Goblin

Haste
Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)

Scourge Servant

Grasp of Darkness

Target creature gets -4/-4 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.

Unholy Indenture

Enchant creature
When enchanted creature dies, return that card to the battlefield under your control with a +1/+1 counter on it.

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.

Whisper of the Dross

Target creature gets -1/-1 until end of turn. Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

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.

Tendrils of Corruption

Tendrils of Corruption deals X damage to target creature and you gain X life, where X is the number of Swamps you control.

Mortuary Mire

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

Typhoid Rats

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

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.)

Cadaver Imp

Flying
When Cadaver Imp enters, you may return target creature card from your graveyard to your hand.

Swamp

Stir the Grave

Return target creature card with mana value X or less from your graveyard to the battlefield.

Vector Asp

{B}: Vector Asp gains infect until end of turn. (It deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)

Gulping Scraptrap

When Gulping Scraptrap enters or dies, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Infectious Inquiry

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

Gloomfang Mauler

Swampcycling {2} ({2}, Discard this card: Search your library for a Swamp card, reveal it, put it into your hand, then shuffle.)
Backup 2 (When this creature enters, put two +1/+1 counters on target creature. If that's another creature, it gains the following ability until end of turn.)
Menace

The Dross Pits

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

Call to the Netherworld

Return target black creature card from your graveyard to your hand.
Madness {0} (If you discard this card, discard it into exile. When you do, cast it for its madness cost or put it into your graveyard.)

Crypt Incursion

Exile all creature cards from target player's graveyard. You gain 3 life for each card exiled this way.