{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.

Charcoal Diamond enters the battlefield tapped. {T}: Add {B}.

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.

{T}: Add one mana of any color. {1}, {T}: Untap target legendary creature you control.

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.

Changeling (This card is every creature type.) As Bloodline Pretender enters the battlefield, choose a creature type. Whenever another creature of the chosen type enters the battlefield under your control, put a +1/+1 counter on Bloodline Pretender.

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

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.

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

Menace As an additional cost to cast black permanent spells, you may pay 2 life. Those spells cost {B} less to cast if you paid life this way. This effect reduces only the amount of black mana you pay. Whenever you cast a black permanent spell, target creature you control gets +1/+1 and gains menace until end of turn.

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

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

When Gnawing Vermin enters the battlefield, target player mills two cards. When Gnawing Vermin dies, target creature you don't control gets -1/-1 until end of turn.

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.)

Bushido 1 (Whenever this creature blocks or becomes blocked, it gets +1/+1 until end of turn.) {1}{B}: Regenerate Kuro's Taken.

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

Ninjutsu {1}{B} ({1}{B}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.) Lifelink

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.

Nezumi Bladeblesser has deathtouch as long as you control an artifact. Nezumi Bladeblesser has menace as long as you control an enchantment. (It can't be blocked except by two or more creatures.)

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

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

Ninjutsu {1}{B} ({1}{B}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.) When Nezumi Prowler enters the battlefield, target creature you control gains deathtouch and lifelink until end of turn.

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.

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.

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

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.

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.

{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.)

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.

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.

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.)

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.)

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.)

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

Add {B}{B}{B}.

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

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

Destroy target creature.

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

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

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

Each opponent loses 1 life for each creature you control.

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.

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