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

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.

When Contagion Clasp enters the battlefield, put a -1/-1 counter on target creature. {4}, {T}: Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

When Contagion Engine enters the battlefield, put a -1/-1 counter on each creature target player controls. {4}, {T}: Proliferate, then proliferate again. (Choose any number of permanents and/or players, then give each another counter of each kind already there. Then do it again.)

Glistening Sphere enters the battlefield tapped. When Glistening Sphere enters the battlefield, proliferate. {T}: Add one mana of any color. Corrupted — {T}: Add three mana of any one color. Activate only if an opponent has three or more poison counters.

{T}: Add {C}{C}.

{T}, Pay 1 life: Destroy target permanent you own. {T}, Pay 2 life: Add one mana of any color. {T}, Pay 3 life: Proliferate. {T}, Pay 4 life: Draw a card. {5}: Untap Staff of Compleation.

Equipped creature has hexproof and haste. (It can't be the target of spells or abilities your opponents control.) Equip {1}

Whenever Ayara, First of Locthwain or another black creature enters the battlefield under your control, each opponent loses 1 life and you gain 1 life. {T}, Sacrifice another black creature: Draw a card.

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.)

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.)

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

When Burglar Rat enters the battlefield, each opponent discards a card.

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.) When Core Prowler dies, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Extort (Whenever you cast a spell, you may pay {W/B}. If you do, each opponent loses 1 life and you gain that much life.) Whenever you tap a Swamp for mana, add an additional {B}.

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

When Disease Carriers dies, target creature gets -2/-2 until end of turn.

When Drainpipe Vermin dies, you may pay {B}. If you do, target player discards a card.

Whenever a Swamp enters the battlefield under your control, choose one — • You draw a card and you lose 1 life. • Dread Presence deals 2 damage to any target and you gain 2 life.

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

When Gray Merchant of Asphodel enters the battlefield, 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.)

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

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 the battlefield, each player gets a poison counter.

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

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.

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

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.

Trample Whenever a source deals damage to Phyrexian Obliterator, that source's controller sacrifices that many permanents.

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.

When Plaguecrafter enters the battlefield, each player sacrifices a creature or planeswalker. Each player who can't discards a card.

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.)

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

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.

{T}: Exile the top card of target player's library. If it's a land card, you gain 1 life. Landfall — Whenever a land enters the battlefield under your control, you may untap Scrib Nibblers.

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.) Whenever Septic Rats attacks, if defending player is poisoned, it gets +1/+1 until end of turn.

When Solemn Simulacrum enters the battlefield, you may search your library for a basic land card, put that card onto the battlefield tapped, then shuffle. When Solemn Simulacrum dies, you may draw a card.

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

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

Add {B}{B}{B}. Threshold — Add {B}{B}{B}{B}{B} instead if seven or more cards are in your graveyard.

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

Add {B}{B}{B}.

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.")

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

Destroy target nonartifact creature.

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.)

Destroy target creature or planeswalker.

Destroy target creature. You lose 2 life.

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

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

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

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

{T}: Add {C}. {4}, {T}: Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

({T}: Add {B}.)

Destroy all creatures. They can't be regenerated.

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

Target creature gets -4/-4 until end of turn. Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Each opponent loses X life. You gain life equal to the life lost this way.

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

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

You draw two cards and you lose 2 life.

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

Target player draws two cards and loses 2 life.

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

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