Whenever you cast a spell, you gain 1 life for each spell you've cast this turn.

Pay 50 life: Aetherflux Reservoir deals 50 damage to any target.

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

Whenever Ashcoat of the Shadow Swarm 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.)

Sacrifice a creature: Add {C}{C}.

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.

When Bastion of Remembrance enters the battlefield, create a 1/1 white Human Soldier creature token.

Whenever a creature you control dies, each opponent loses 1 life and you gain 1 life.

Bojuka Bog enters the battlefield tapped.

When Bojuka Bog enters the battlefield, exile target player's graveyard.

{T}: Add {B}.

You may look at the top card of your library any time.

You may play lands and cast spells from the top of your library. If you cast a spell this way, pay life equal to its mana value rather than pay its mana cost.

{T}, Sacrifice ten nonland permanents: Each opponent loses 10 life.

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.

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

{T}: Add {C}.

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

As Caged Sun enters the battlefield, choose a color.

Creatures you control of the chosen color get +1/+1.

Whenever a land's ability causes you to add one or more mana of the chosen color, add one additional mana of that color.

Castle Locthwain enters the battlefield 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.

When Chittering Witch enters the battlefield, create a number of 1/1 black Rat creature tokens equal to the number of opponents you have.

{1}{B}, Sacrifice a creature: Target creature gets -2/-2 until end of turn.

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.)

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}.

Crypt of Agadeem enters the battlefield tapped.

{T}: Add {B}.

{2}, {T}: Add {B} for each black creature card in your graveyard.

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

Add {B}{B}{B}.

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

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.)

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

Changeling (This card is every creature type.)

When Graveshifter enters the battlefield, you may return target creature card from your graveyard to your hand.

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.)

Commander creatures you own have "Whenever this creature becomes tapped, it and other creatures you control that share a creature type with it each get +2/+0 and gain undying until end of turn." (When a creature with undying dies, if it had no +1/+1 counters on it, return it to the battlefield under its owner's control with a +1/+1 counter on it.)

As Herald's Horn enters the battlefield, choose a creature type.

Creature spells you cast of the chosen type cost {1} less to cast.

At the beginning of your upkeep, look at the top card of your library. If it's a creature card of the chosen type, you may reveal it and put it into your hand.

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.

Destroy target creature. You lose 2 life.

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, Servant of Oni 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.

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

{T}: Add {C}.

{4}, {T}: 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.)

Other Rats you control have toxic 1.

When Karumonix enters the battlefield, 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.

+1: Search your library for a Swamp card, reveal it, put it into your hand, then shuffle.

-3: Target creature gets +X/+X or -X/-X until end of turn, where X is the number of Swamps you control.

-6: You get an emblem with "Swamps you control have '{T}: Add {B}{B}{B}{B}.'"

Whenever another Rat enters the battlefield under your control, 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 creature can't block."

Choose target creature. You lose 2 life. Until end of turn, that creature gains "When this creature dies, return it to the battlefield tapped under its owner's control."

Malakir Mire enters the battlefield tapped.

{T}: Add {B}.

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.

Flying

Whenever you create or sacrifice a token, each opponent loses 1 life.

Mortuary Mire enters the battlefield tapped.

When Mortuary Mire enters the battlefield, you may put target creature card from your graveyard on top of your library.

{T}: Add {B}.

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

Myriad Landscape enters the battlefield tapped.

{T}: Add {C}.

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

Ninjutsu {3}{B} ({3}{B}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.)

Whenever Nashi, Moon Sage's Scion deals combat damage to a player, exile the top card of each player's library. Until end of turn, you may play one of those cards. If you cast a spell this way, pay life equal to its mana value rather than paying its mana cost.

{T}: Add {C}.

{2}, {T}: Choose a color. Add an amount of mana of that color equal to your devotion to that color. (Your devotion to a color is the number of mana symbols of that color in the mana costs of permanents you control.)

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.)

As Obelisk of Urd enters the battlefield, choose a creature type.

Creatures you control of the chosen type get +2/+2.

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

Rats you control have deathtouch.

At the beginning of your upkeep, if you have four or more creature cards in your graveyard, you may return target creature card from your graveyard to your hand.

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.

Whenever an opponent casts a spell, that player loses 5 life unless they discard a card.

Each player chooses a creature type. Each player returns all creature cards of a type chosen this way from their graveyard to the battlefield.

Rat offering (You may cast this card any time you could cast an instant by sacrificing a Rat and paying the difference in mana costs between this and the sacrificed Rat. Mana cost includes color.)

Whenever a permanent is put into an opponent's graveyard, that player loses 1 life.

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

{1}{B}, Pay 2 life: Return target creature card from your graveyard to your hand.

{T}: Add {C}.

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

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.

Starting with you, each player may pay any amount of life. Repeat this process until no one pays life. Each player creates a 1/1 black Rat creature token for each 1 life they paid this way.

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.

You have no maximum hand size.

{T}: Add {C}.

{T}: Add {C}.

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

Deathtouch

Whenever you draw a card, you gain 2 life.

Whenever an opponent draws a card, they lose 2 life.

{T}: Add {B}.

{B}, {T}: Target legendary creature gains fear until end of turn. (It can't be blocked except by artifact creatures and/or black creatures.)

Equipped creature gets +1/-1.

Whenever equipped creature dies, draw two cards.

Equip {1}

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

As Species Specialist enters the battlefield, choose a creature type.

Whenever a creature of the chosen type dies, you may draw a card.

Equipped creature gets +1/+1 and has haste.

At the beginning of each combat, untap equipped creature.

Equipped creature has first strike as long as it's blocking or blocked by a Goblin or Orc.

Equip {2}

({T}: Add {B}.)

({T}: Add {B}.)

({T}: Add {B}.)

({T}: Add {B}.)

({T}: Add {B}.)

({T}: Add {B}.)

({T}: Add {B}.)

({T}: Add {B}.)

({T}: Add {B}.)

({T}: Add {B}.)

({T}: Add {B}.)

({T}: Add {B}.)

({T}: Add {B}.)

({T}: Add {B}.)

({T}: Add {B}.)

({T}: Add {B}.)

({T}: Add {B}.)

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

{T}: Add {C}.

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

Whenever another creature dies, or a creature card is put into a graveyard from anywhere other than the battlefield, or a creature card leaves your graveyard, Syr Konrad, the Grim deals 1 damage to each opponent.

{1}{B}: Each player mills a card. (They each put the top card of their library into their graveyard.)

Tangled Colony can't block.

When Tangled Colony dies, create X 1/1 black Rat creature tokens with "This creature can't block," where X is the amount of damage dealt to it this turn.

Equipped creature has "{2}, {T}: This creature deals 1 damage to any target" and "Whenever a creature dies, untap this creature."

Whenever a Shaman creature enters the battlefield, you may attach Thornbite Staff to it.

Equip {4}

As an additional cost to cast this spell, pay X life.

All creatures get -X/-X until end of turn.

When Twisted Sewer-Witch enters the battlefield, create a 1/1 black Rat creature token with "This creature can't block." Then for each Rat you control, create a Wicked Role token attached to that Rat. (If you control another Role on it, put that one into the graveyard. Enchanted creature gets +1/+1. When this Aura is put into a graveyard, each opponent loses 1 life.)

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

Target creature gains undying until end of turn. (When it dies, if it had no +1/+1 counters on it, return it to the battlefield under its owner's control with a +1/+1 counter on it.)

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."

Each land is a Swamp in addition to its other land types.

{1}{B}, Sacrifice a creature: You gain 1 life and draw a card.

Search your library for a card, then shuffle and put that card on top. You lose 2 life.

As Vanquisher's Banner enters the battlefield, choose a creature type.

Creatures you control of the chosen type get +1/+1.

Whenever you cast a creature spell of the chosen type, draw a card.

When Voracious Vermin enters the battlefield, 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.

{T}: Add {C}.

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

Trample

When Wave of Rats dies, if it dealt combat damage to a player this turn, return it to the battlefield under its owner's control.

Blitz {4}{B} (If you cast this spell for its blitz cost, it gains haste and "When this creature dies, draw a card." Sacrifice it at the beginning of the next end step.)

({T}: Add {B}.)

Witch's Cottage enters the battlefield tapped unless you control three or more other Swamps.

When Witch's Cottage enters the battlefield untapped, you may put target creature card from your graveyard on top of your library.

Whenever Zulaport Cutthroat or another creature you control dies, each opponent loses 1 life and you gain 1 life.