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.

Black creatures get +1/+1.

Whenever a creature dies, put a charge counter on Black Market.

At the beginning of your precombat main phase, add {B} for each charge counter on Black Market.

Bog Rats can't be blocked by Walls.

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.

Whenever Carrion Rats attacks or blocks, any player may exile a card from their graveyard. If a player does, Carrion Rats assigns no combat damage this turn.

When Chittering Rats enters the battlefield, target opponent puts a card from their hand on top of their library.

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.

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

Sacrifice Commander's Sphere: Draw a card.

Choose a creature type. Creatures that aren't of the chosen type get -3/-3 until end of turn.

Crypt of Agadeem enters the battlefield tapped.

{T}: Add {B}.

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

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

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

This spell costs {X} less to cast, where X is your devotion to black. (Each {B} in the mana costs of permanents you control counts toward your devotion to black.)

Destroy target creature.

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

When Earsplitting Rats enters the battlefield, each player discards a card.

Discard a card: Regenerate Earsplitting Rats.

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

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

At the beginning of combat on your turn, if you both own and control Graf Rats and a creature named Midnight Scavengers, exile them, then meld them into Chittering Host.

Each opponent loses 1 life for each creature you control.

Choose a creature type. Return up to two creature cards of that type from your graveyard to the battlefield. If this spell was foretold, return all creature cards of that type from your graveyard to the battlefield instead.

Foretell {5}{B}{B} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)

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.

As Heraldic Banner enters the battlefield, choose a color.

Creatures you control of the chosen color get +1/+0.

{T}: Add one mana of the chosen color.

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.

{2}{B}: Infected Vermin deals 1 damage to each creature and each player.

Threshold -- {3}{B}: Infected Vermin deals 3 damage to each creature and each player. Activate only if seven or more cards are in your graveyard.

Bushido 1 (Whenever this creature blocks or becomes blocked, it gets +1/+1 until end of turn.)

{1}{B}: Regenerate Kuro's Taken.

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.

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}.

Destroy target creature.

{T}: Add {C}.

{1}: Mutavault becomes a 2/2 creature with all creature types until end of turn. It's still a land.

{B}, Sacrifice a creature: Target player discards a card. Activate only as a sorcery.

{1}{B}: Exile target card from an opponent's graveyard. If no cards are in that graveyard, flip Nezumi Graverobber.

{4}{B}: Put target creature card from a graveyard onto the battlefield under your control.

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

Rats you control have deathtouch.

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 Okiba-Gang Shinobi deals combat damage to a player, that player discards two cards.

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.

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.

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.)

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.

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.

When Ravenous Rats enters the battlefield, target opponent discards a card.

Fear (This creature can't be blocked except by artifact creatures and/or black creatures.)

{T}: Add {C}.

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

When Rotting Rats enters the battlefield, each player discards a card.

Unearth {1}{B} ({1}{B}: Return this card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the next end step or if it would leave the battlefield. Unearth only as a sorcery.)

Deathtouch

When Ruin Rat dies, exile target card from an opponent's graveyard.

{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.

{B}, Pay 1 life: Sewer Rats gets +1/+0 until end of turn. Activate no more than three times each turn.

{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.)

Equipped creature gets +1/-1.

Whenever equipped creature dies, draw two cards.

Equip {1}

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

Whenever Skullsnatcher deals combat damage to a player, exile up to two target cards from that player's graveyard.

{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.

Shadow (This creature can block or be blocked by only creatures with shadow.)

Whenever Stronghold Rats deals combat damage to a player, each player discards a card.

({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}.)

({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}.)

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}

When Thriving Rats enters the battlefield, you get {E}{E} (two energy counters).

Whenever Thriving Rats attacks, you may pay {E}{E}. If you do, put a +1/+1 counter on it.

Ninjutsu {2}{B} ({2}{B}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.)

Whenever Throat Slitter deals combat damage to a player, destroy target nonblack creature that player controls.

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

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.

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

Draw two cards.

Equipped creature gets +2/+0 and has deathtouch.

{5}{B}{B}{B}: Until end of turn, Vorpal Sword gains "Whenever equipped creature deals combat damage to a player, that player loses the game."

Equip {B}{B}