Rat Colony

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

Tetsuko Umezawa, Fugitive

Creatures you control with power or toughness 1 or less can't be blocked.

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.

Dragon Tempest

Whenever a creature you control with flying enters, it gains haste until end of turn.
Whenever a Dragon you control enters, it deals X damage to any target, where X is the number of Dragons you control.

Scourge of Valkas

Flying
Whenever Scourge of Valkas or another Dragon you control enters, it deals X damage to any target, where X is the number of Dragons you control.
{R}: Scourge of Valkas gets +1/+0 until end of turn.

Arcane Adaptation

As Arcane Adaptation enters, choose a creature type.
Creatures you control are the chosen type in addition to their other types. The same is true for creature spells you control and creature cards you own that aren't on the battlefield.

The Ur-Dragon

Eminence — As long as The Ur-Dragon is in the command zone or on the battlefield, other Dragon spells you cast cost {1} less to cast.
Flying
Whenever one or more Dragons you control attack, draw that many cards, then you may put a permanent card from your hand onto the battlefield.

Atarka, World Render

Flying, trample
Whenever a Dragon you control attacks, it gains double strike until end of turn.

Dromoka, the Eternal

Flying
Whenever a Dragon you control attacks, bolster 2. (Choose a creature with the least toughness among creatures you control and put two +1/+1 counters on it.)

Kolaghan, the Storm's Fury

Flying
Whenever a Dragon you control attacks, creatures you control get +1/+0 until end of turn.
Dash {3}{B}{R} (You may cast this spell for its dash cost. If you do, it gains haste, and it's returned from the battlefield to its owner's hand at the beginning of the next end step.)

Ojutai, Soul of Winter

Flying, vigilance
Whenever a Dragon you control attacks, tap target nonland permanent an opponent controls. That permanent doesn't untap during its controller's next untap step.

Silumgar, the Drifting Death

Flying, hexproof
Whenever a Dragon you control attacks, creatures defending player controls get -1/-1 until end of turn.

Hour of Promise

Search your library for up to two land cards, put them onto the battlefield tapped, then shuffle. Then if you control three or more Deserts, create two 2/2 black Zombie creature tokens.

Ghirapur Orrery

Each player may play an additional land on each of their turns.
At the beginning of each player's upkeep, if that player has no cards in hand, that player draws three cards.

Maze's End

Maze's End enters tapped.
{T}: Add {C}.
{3}, {T}, Return Maze's End to its owner's hand: Search your library for a Gate card, put it onto the battlefield, then shuffle. If you control ten or more Gates with different names, you win the game.

Ogre Slumlord

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

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.

Time Reversal

Each player shuffles their hand and graveyard into their library, then draws seven cards. Exile Time Reversal.

Xenograft

As Xenograft enters, choose a creature type.
Each creature you control is the chosen type in addition to its other types.

Conspiracy

As Conspiracy enters, choose a creature type.
Creatures you control are the chosen type. The same is true for creature spells you control and creature cards you own that aren't on the battlefield.

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.

Patriarch's Bidding

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

Plague Rats

Plague Rats's power and toughness are each equal to the number of creatures named Plague Rats on the battlefield.

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.)

Game Plan

Assist (Another player can pay up to {5} of this spell's cost.)
Each player shuffles their hand and graveyard into their library, then draws seven cards. Exile Game Plan.

Sylvia Brightspear

Partner with Khorvath Brightflame (When this creature enters, target player may put Khorvath into their hand from their library, then shuffle.)
Double strike
Dragons your team controls have double strike.

Blinkmoth Urn

At the beginning of each player's first main phase, if Blinkmoth Urn is untapped, that player adds {C} for each artifact they control.

Selesnya Guildgate

Selesnya Guildgate enters tapped.
{T}: Add {G} or {W}.

Dimir Guildgate

Dimir Guildgate enters tapped.
{T}: Add {U} or {B}.

Circuitous Route

Search your library for up to two basic land cards and/or Gate cards, put them onto the battlefield tapped, then shuffle.

Selesnya Signet

Golgari Signet

Dimir Signet

Emergency Powers

Each player shuffles their hand and graveyard into their library, then draws seven cards. Exile Emergency Powers.
Addendum — If you cast this spell during your main phase, you may put a permanent card with mana value 7 or less from your hand onto the battlefield.

Gruul Guildgate

Gruul Guildgate enters tapped.
{T}: Add {R} or {G}.

Azorius Guildgate

Azorius Guildgate enters tapped.
{T}: Add {W} or {U}.

Simic Signet

Orzhov Guildgate

Orzhov Guildgate enters tapped.
{T}: Add {W} or {B}.

Echo of Eons

Each player shuffles their hand and graveyard into their library, then draws seven cards.
Flashback {2}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Golos, Tireless Pilgrim

When Golos, Tireless Pilgrim enters, you may search your library for a land card, put that card onto the battlefield tapped, then shuffle.
{2}{W}{U}{B}{R}{G}: Exile the top three cards of your library. You may play them this turn without paying their mana costs.

Thespian's Stage

{T}: Add {C}.
{2}, {T}: Thespian's Stage becomes a copy of target land, except it has this ability.

Simic Guildgate

Simic Guildgate enters tapped.
{T}: Add {G} or {U}.

Golgari Guildgate

Golgari Guildgate enters tapped.
{T}: Add {B} or {G}.

Izzet Guildgate

Izzet Guildgate enters tapped.
{T}: Add {U} or {R}.

Boros Guildgate

Boros Guildgate enters tapped.
{T}: Add {R} or {W}.

Rakdos Guildgate

Rakdos Guildgate enters tapped.
{T}: Add {B} or {R}.

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.

Gateway Plaza

Gateway Plaza enters tapped.
When Gateway Plaza enters, sacrifice it unless you pay {1}.
{T}: Add one mana of any color.

Gruul Signet

Burnished Hart

{3}, Sacrifice Burnished Hart: Search your library for up to two basic land cards, put them onto the battlefield tapped, then shuffle.

Bladewing the Risen

Flying
When Bladewing the Risen enters, you may return target Dragon permanent card from your graveyard to the battlefield.
{B}{R}: Dragon creatures get +1/+1 until end of turn.

Tempt with Discovery

Tempting offer — Search your library for a land card and put it onto the battlefield. Each opponent may search their library for a land card and put it onto the battlefield. For each opponent who searches a library this way, search your library for a land card and put it onto the battlefield. Then each player who searched a library this way shuffles.

Impact Tremors

Whenever a creature you control enters, Impact Tremors deals 1 damage to each opponent.

Idyllic Tutor

Search your library for an enchantment card, reveal it, put it into your hand, then shuffle.

Forest

Mountain

Swamp

Island

Plains

Arcane Signet

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

Command Tower

Commander's Sphere

{T}: Add one mana of any color in your commander's color identity.
Sacrifice Commander's Sphere: Draw a card.

Sol Ring

The Locust God

Flying
Whenever you draw a card, create a 1/1 blue and red Insect creature token with flying and haste.
{2}{U}{R}: Draw a card, then discard a card.
When The Locust God dies, return it to its owner's hand at the beginning of the next end step.

Myriad Landscape

Myriad Landscape enters 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.

Solemn Simulacrum

When Solemn Simulacrum enters, you may search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.
When Solemn Simulacrum dies, you may draw a card.

Orzhov Signet

Rakdos Signet

Izzet Signet

Azorius Signet

Boros Signet

Kodama's Reach

Search your library for up to two basic land cards, reveal those cards, put one onto the battlefield tapped and the other into your hand, then shuffle.