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.

Tangled Colony

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

Reliquary Tower

You have no maximum hand size.
{T}: Add {C}.

Diabolic Tutor

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

Blooming Marsh

This land enters tapped unless you control two or fewer other lands.
{T}: Add {B} or {G}.

Zagoth Triome

({T}: Add {B}, {G}, or {U}.)
This land enters tapped.
Cycling {3} ({3}, Discard this card: Draw a card.)

Forest

Complicate

Counter target spell unless its controller pays {3}.
Cycling {2}{U} ({2}{U}, Discard this card: Draw a card.)
When you cycle this card, you may counter target spell unless its controller pays {1}.

Primal Vigor

If one or more tokens would be created, twice that many of those tokens are created instead.
If one or more +1/+1 counters would be put on a creature, twice that many +1/+1 counters are put on that creature instead.

Copy Enchantment

You may have this enchantment enter as a copy of any enchantment on the battlefield.

Drowned Catacomb

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

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.

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.

Protean Hulk

When this creature dies, search your library for any number of creature cards with total mana value 6 or less, put them onto the battlefield, then shuffle.

Demonic Tutor

Mystical Dispute

This spell costs {2} less to cast if it targets a blue spell.
Counter target spell unless its controller pays {3}.

Amulet of Vigor

Whenever a permanent you control enters tapped, untap it.

Island

Urborg, Tomb of Yawgmoth

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

Exploration

You may play an additional land on each of your turns.

Pestilence Rats

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.)

Doubling Season

If an effect would create one or more tokens under your control, it creates twice that many of those tokens instead.
If an effect would put one or more counters on a permanent you control, it puts twice that many of those counters on that permanent instead.

Folio of Fancies

Players have no maximum hand size.
{X}{X}, {T}: Each player draws X cards.
{2}{U}, {T}: Each opponent mills cards equal to the number of cards in their hand.

Dark Ritual

Breeding Pool

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

Parallel Lives

If an effect would create one or more tokens under your control, it creates twice that many of those tokens instead.

Vampiric Tutor

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

Mox Amber

{T}: Add one mana of any color among legendary creatures and planeswalkers you control.

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.

Mirror Box

The "legend rule" doesn't apply to permanents you control.
Each legendary creature you control gets +1/+1.
Each nontoken creature you control gets +1/+1 for each other creature you control with the same name as that creature.

City of Solitude

Players can cast spells and activate abilities only during their own turns.

Swarm of Rats

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

Mirrormade

You may have this enchantment enter as a copy of any artifact or enchantment on the battlefield.

Ashnod's Altar

Tamiyo, Compleated Sage

Compleated ({G/U/P} can be paid with {G}, {U}, or 2 life. If life was paid, this planeswalker enters with two fewer loyalty counters.)
+1: Tap up to one target artifact or creature. It doesn't untap during its controller's next untap step.
−X: Exile target nonland permanent card with mana value X from your graveyard. Create a token that's a copy of that card.
−7: Create Tamiyo's Notebook, a legendary colorless artifact token with "Spells you cast cost {2} less to cast" and "{T}: Draw a card."

Kruphix, God of Horizons

Indestructible
As long as your devotion to green and blue is less than seven, Kruphix isn't a creature.
You have no maximum hand size.
If you would lose unspent mana, that mana becomes colorless instead.

Phyrexian Altar

Sacrifice a creature: Add one mana of any color.

Kindred Discovery

As this enchantment enters, choose a creature type.
Whenever a creature you control of the chosen type enters or attacks, draw a card.

Botanical Sanctum

This land enters tapped unless you control two or fewer other lands.
{T}: Add {G} or {U}.

Fierce Guardianship

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

Swamp

Palinchron

Flying
When this creature enters, untap up to seven lands.
{2}{U}{U}: Return this creature to its owner's hand.

Relentless Rats

This creature gets +1/+1 for each other creature on the battlefield named Relentless Rats.
A deck can have any number of cards named Relentless Rats.

Watery Grave

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

Oracle of Mul Daya

You may play an additional land on each of your turns.
Play with the top card of your library revealed.
You may play lands from the top of your library.

Wild Pair

Whenever a creature enters, if you cast it from your hand, you may search your library for a creature card with the same total power and toughness, put it onto the battlefield, then shuffle.

Nim Deathmantle

Equipped creature gets +2/+2, has intimidate, and is a black Zombie. (A creature with intimidate can't be blocked except by artifact creatures and/or creatures that share a color with it.)
Whenever a nontoken creature is put into your graveyard from the battlefield, you may pay {4}. If you do, return that card to the battlefield and attach this Equipment to it.
Equip {4}

Shipwreck Marsh

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

Adrix and Nev, Twincasters

Ward {2} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {2}.)
If one or more tokens would be created under your control, twice that many of those tokens are created instead.

Deathcap Glade

This land enters tapped unless you control two or more other lands.
{T}: Add {B} or {G}.

Diamond Valley

{T}, Sacrifice a creature: You gain life equal to the sacrificed creature's toughness.

Rites of Flourishing

At the beginning of each player's draw step, that player draws an additional card.
Each player may play an additional land on each of their turns.

Koskun Falls

At the beginning of your upkeep, sacrifice this enchantment unless you tap an untapped creature you control.
Creatures can't attack you unless their controller pays {2} for each creature they control that's attacking you.

Twisted Sewer-Witch

When this creature enters, 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 token is put into a graveyard, each opponent loses 1 life.)

Cyclonic Rift

Return target nonland permanent you don't control to its owner's hand.
Overload {6}{U} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Ashaya, Soul of the Wild

Ashaya's power and toughness are each equal to the number of lands you control.
Nontoken creatures you control are Forest lands in addition to their other types. (They're still affected by summoning sickness.)

Ogre Slumlord

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

Nashi, Moon's Legacy

Menace, ward {1}
Whenever Nashi attacks, exile up to one target legendary or Rat card from your graveyard and copy it. You may cast the copy. (You still pay its costs. A copy of a permanent spell becomes a token.)

Dreamroot Cascade

This land enters tapped unless you control two or more other lands.
{T}: Add {G} or {U}.

Overgrown Tomb

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

Jin-Gitaxias, Progress Tyrant

Whenever you cast an artifact, instant, or sorcery spell, copy that spell. You may choose new targets for the copy. This ability triggers only once each turn. (A copy of a permanent spell becomes a token.)
Whenever an opponent casts an artifact, instant, or sorcery spell, counter that spell. This ability triggers only once each turn.

Reflections of Littjara

As this enchantment enters, choose a creature type.
Whenever you cast a spell of the chosen type, copy that spell. (A copy of a permanent spell becomes a token.)

Isochron Scepter

Imprint — When this artifact enters, you may exile an instant card with mana value 2 or less from your hand.
{2}, {T}: You may copy the exiled card. If you do, you may cast the copy without paying its mana cost.

Dramatic Reversal

Untap all nonland permanents you control.

The Reality Chip

You may look at the top card of your library any time.
As long as The Reality Chip is attached to a creature, you may play lands and cast spells from the top of your library.
Reconfigure {2}{U} ({2}{U}: Attach to target creature you control; or unattach from a creature. Reconfigure only as a sorcery. While attached, this isn't a creature.)

Rat Colony

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

Typhoid Rats

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

Lion's Eye Diamond

Discard your hand, Sacrifice this artifact: Add three mana of any one color. Activate only as an instant.

Root Maze

Gilded Lotus

Gemstone Caverns

If this card is in your opening hand and you're not the starting player, you may begin the game with Gemstone Caverns on the battlefield with a luck counter on it. If you do, exile a card from your hand.
{T}: Add {C}. If Gemstone Caverns has a luck counter on it, instead add one mana of any color.

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 this creature.

Lotus Petal

{T}, Sacrifice this artifact: Add one mana of any color.

Extravagant Replication

At the beginning of your upkeep, create a token that's a copy of another target nonland permanent you control.

Storm Cauldron

Each player may play an additional land during each of their turns.
Whenever a land is tapped for mana, return it to its owner's hand.

Darkslick Shores

This land enters tapped unless you control two or fewer other lands.
{T}: Add {U} or {B}.

Woodland Cemetery

This land enters tapped unless you control a Swamp or a Forest.
{T}: Add {B} or {G}.

Estrid's Invocation

You may have this enchantment enter as a copy of an enchantment you control, except it has "At the beginning of your upkeep, you may exile this enchantment. If you do, return it to the battlefield under its owner's control."

Sol Ring

Hinterland Harbor

This land enters tapped unless you control a Forest or an Island.
{T}: Add {G} or {U}.

Mana Crypt

At the beginning of your upkeep, flip a coin. If you lose the flip, this artifact deals 3 damage to you.
{T}: Add {C}{C}.

Season of the Witch

At the beginning of your upkeep, sacrifice this enchantment unless you pay 2 life.
At the beginning of the end step, destroy all untapped creatures that didn't attack this turn, except for creatures that couldn't attack.

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 token can't block."