Rapid Hybridization

Destroy target creature. It can't be regenerated. That creature's controller creates a 3/3 green Frog Lizard creature token.

Vren, the Relentless

Ward {2}
If a creature an opponent controls would die, exile it instead.
At the beginning of each end step, create X 1/1 black Rat creature tokens with "This creature gets +1/+1 for each other Rat you control," where X is the number of creatures that were exiled under your opponents' control this turn.

Swarmyard Massacre

Create two 1/1 green Squirrel creature tokens. Then each creature that isn't an Insect, Rat, Spider, or Squirrel gets -1/-1 until end of turn for each creature you control that's an Insect, Rat, Spider, or Squirrel.

Vampiric Tutor

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

Cabal Coffers

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

Cover of Darkness

As Cover of Darkness enters, choose a creature type.
Creatures of the chosen type have fear. (They can't be blocked except by artifact creatures and/or black creatures.)

Piper of the Swarm

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.

Septic Rats

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.

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.

Tidecaller Mentor

Menace
Threshold — When Tidecaller Mentor enters, if seven or more cards are in your graveyard, return up to one target nonland permanent to its owner's hand.

Ashcoat of the Shadow Swarm

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.)

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.)

Polluted Delta

{T}, Pay 1 life, Sacrifice Polluted Delta: Search your library for an Island or Swamp card, put it onto the battlefield, then shuffle.

Azure Beastbinder

Vigilance
Azure Beastbinder can't be blocked by creatures with power 2 or greater.
Whenever Azure Beastbinder attacks, up to one target artifact, creature, or planeswalker an opponent controls loses all abilities until your next turn. If it's a creature, it also has base power and toughness 2/2 until your next turn.

Valley Rotcaller

Menace
Whenever Valley Rotcaller attacks, each opponent loses X life and you gain X life, where X is the number of other Squirrels, Bats, Lizards, and Rats you control.

Otawara, Soaring City

{T}: Add {U}.
Channel — {3}{U}, Discard Otawara, Soaring City: Return target artifact, creature, enchantment, or planeswalker to its owner's hand. This ability costs {1} less to activate for each legendary creature you control.

Swarmyard

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

Shoreline Looter

Shoreline Looter can't be blocked.
Threshold — Whenever Shoreline Looter deals combat damage to a player, draw a card. Then discard a card unless seven or more cards are in your graveyard.

Ogre Slumlord

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

Spark Double

You may have Spark Double enter as a copy of a creature or planeswalker you control, except it enters with an additional +1/+1 counter on it if it's a creature, it enters with an additional loyalty counter on it if it's a planeswalker, and it isn't legendary.

Thornplate Intimidator

Offspring {3} (You may pay an additional {3} as you cast this spell. If you do, when this creature enters, create a 1/1 token copy of it.)
When this creature enters, target opponent loses 3 life unless they sacrifice a nonland permanent of their choice or discard a card.

Psychic Whorl

Target opponent discards two cards. Then if you control a Rat, surveil 2. (Look at the top two cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)

Swamp

Brainstorm

Draw three cards, then put two cards from your hand on top of your library in any order.

Shipwreck Marsh

Shipwreck Marsh enters tapped unless you control two or more other lands.
{T}: Add {U} or {B}.

Patchwork Banner

As Patchwork Banner enters, choose a creature type.
Creatures you control of the chosen type get +1/+1.
{T}: Add one mana of any color.

Fabled Passage

{T}, Sacrifice Fabled Passage: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle. Then if you control four or more lands, untap that land.

Sol Ring

Don't Make a Sound

Counter target spell unless its controller pays {2}. If they do, surveil 2. (Look at the top two cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)

Priest of Forgotten Gods

{T}, Sacrifice two other creatures: Any number of target players each lose 2 life and sacrifice a creature of their choice. You add {B}{B} and draw a card.

Mana Drain

Counter target spell. At the beginning of your next main phase, add an amount of {C} equal to that spell's mana value.

Mindwhisker

At the beginning of your upkeep, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)
Threshold — As long as seven or more cards are in your graveyard, creatures your opponents control get -1/-0.

Bontu's Monument

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.

Demonic Tutor

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

Plague of Vermin

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.

Fish

Ratcatcher

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.

Gruesome Fate

Each opponent loses 1 life for each creature you control.

Island

Arcane Signet

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

Command Tower

Ink-Eyes, Servant of Oni

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.

Wave of Rats

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.)

Revenge of the Rats

Create a tapped 1/1 black Rat creature token for each creature card in your graveyard.
Flashback {2}{B}{B} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Urborg, Tomb of Yawgmoth

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

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.)

Sunken Hollow

({T}: Add {U} or {B}.)
Sunken Hollow enters tapped unless you control two or more basic lands.

Old Flitterfang

Flying
At the beginning of each end step, if a creature died this turn, create a Food token. (It's an artifact with "{2}, {T}, Sacrifice this artifact: You gain 3 life.")
{2}{B}, Sacrifice another creature or artifact: Old Flitterfang gets +2/+2 until end of turn.

Negate

Gossip's Talent

(Gain the next level as a sorcery to add its ability.)
Whenever a creature you control enters, surveil 1.
{1}{U}: Level 2
Whenever you attack, target attacking creature with power 3 or less can't be blocked this turn.
{3}{U}: Level 3
Whenever a creature you control deals combat damage to a player, you may exile it, then return it to the battlefield under its owner's control.

Counterspell

Takenuma, Abandoned Mire

{T}: Add {B}.
Channel — {3}{B}, Discard Takenuma, Abandoned Mire: Mill three cards, then return a creature or planeswalker card from your graveyard to your hand. This ability costs {1} less to activate for each legendary creature you control.

Countersquall

Counter target noncreature spell. Its controller loses 2 life.

Dimir Signet

The Meathook Massacre

When The Meathook Massacre enters, each creature gets -X/-X until end of turn.
Whenever a creature you control dies, each opponent loses 1 life.
Whenever a creature an opponent controls dies, you gain 1 life.

Marrow-Gnawer

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.

Watery Grave

({T}: Add {U} or {B}.)
As Watery Grave enters, you may pay 2 life. If you don't, it enters tapped.

Consumed by Greed

Gift a card (You may promise an opponent a gift as you cast this spell. If you do, they draw a card before its other effects.)
Target opponent sacrifices a creature with the greatest power among creatures they control. If the gift was promised, return target creature card from your graveyard to your hand.

Mudflat Village

{T}: Add {C}.
{T}: Add {B}. Spend this mana only to cast a creature spell.
{1}{B}, {T}, Sacrifice Mudflat Village: Return target Bat, Lizard, Rat, or Squirrel card from your graveyard to your hand.

When this creature enters, target opponent loses 3 life unless they sacrifice a nonland permanent or discard a card.
(This token's mana cost is {3}{B}.)

Food

{2}, {T}, Sacrifice this artifact: You gain 3 life.

Skullclamp

Equipped creature gets +1/-1.
Whenever equipped creature dies, draw two cards.
Equip {1}

Path of Ancestry

Path of Ancestry enters tapped.
{T}: Add one mana of any color in your commander's color identity. When that mana is spent to cast a creature spell that shares a creature type with your commander, scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Thornbite Staff

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, you may attach Thornbite Staff to it.
Equip {4}

Lilypad Village

{T}: Add {C}.
{T}: Add {U}. Spend this mana only to cast a creature spell.
{U}, {T}: Surveil 2. Activate only if a Bird, Frog, Otter, or Rat entered the battlefield under your control this turn.

Deadly Rollick

If you control a commander, you may cast this spell without paying its mana cost.
Exile target creature.

Season of Loss

Choose up to five {P} worth of modes. You may choose the same mode more than once.
{P} — Each player sacrifices a creature of their choice.
{P}{P} — Draw a card for each creature that died under your control this turn.
{P}{P}{P} — Each opponent loses X life, where X is the number of creature cards in your graveyard.

Ayara, First of Locthwain

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

This creature gets +1/+1 for each other Rat you control.

Diresight

Surveil 2, then draw two cards. You lose 2 life. (To surveil 2, look at the top two cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)

Vat of Rebirth

Whenever another artifact or creature you control is put into a graveyard from the battlefield, put an oil counter on Vat of Rebirth.
{2}{B}, {T}, Remove four oil counters from Vat of Rebirth: Return target creature card from your graveyard to the battlefield. Activate only as a sorcery.

Pack Rat

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.

Drowned Catacomb

Drowned Catacomb enters tapped unless you control an Island or a Swamp.
{T}: Add {U} or {B}.

Helm of the Host

At the beginning of combat on your turn, create a token that's a copy of equipped creature, except the token isn't legendary. That token gains haste.
Equip {5}

City's Blessing

Undercity Sewers

({T}: Add {U} or {B}.)
Undercity Sewers enters tapped.
When Undercity Sewers enters, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)

Copy

(This token can be used to represent a token that's a copy of a permanent.)

Lord Skitter's Butcher

When Lord Skitter's Butcher enters, choose one —
• Create a 1/1 black Rat creature token with "This creature can't block."
• You may sacrifice another creature. If you do, scry 2, then draw a card.
• Creatures you control gain menace until end of turn.

The One Ring

Indestructible
When The One Ring enters, if you cast it, you gain protection from everything until your next turn.
At the beginning of your upkeep, you lose 1 life for each burden counter on The One Ring.
{T}: Put a burden counter on The One Ring, then draw a card for each burden counter on The One Ring.

Frog Lizard

Wick's Patrol

When Wick's Patrol enters, mill three cards. When you do, target creature an opponent controls gets -X/-X until end of turn, where X is the greatest mana value among cards in your graveyard.

Vona's Hunger

Ascend (If you control ten or more permanents, you get the city's blessing for the rest of the game.)
Each opponent sacrifices a creature of their choice. If you have the city's blessing, instead each opponent sacrifices half the creatures they control of their choice, rounded up.

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}.

Filth

Swampwalk (This creature can't be blocked as long as defending player controls a Swamp.)
As long as Filth is in your graveyard and you control a Swamp, creatures you control have swampwalk.

Pongify

Destroy target creature. It can't be regenerated. Its controller creates a 3/3 green Ape creature token.

Jet Medallion

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

Squirrel

Plaguecrafter

When Plaguecrafter enters, each player sacrifices a creature or planeswalker of their choice. Each player who can't discards a card.

Lord Skitter, Sewer King

Whenever another Rat you control enters, 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."

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.

Fell

Cavern of Souls

As Cavern of Souls enters, choose a creature type.
{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to cast a creature spell of the chosen type, and that spell can't be countered.

Mind Drill Assailant

Threshold — As long as seven or more cards are in your graveyard, Mind Drill Assailant gets +3/+0.
{2}{U/B}: Surveil 1. (Look at the top card of your library. You may put it into your graveyard.)