Assert Perfection

Target creature you control gets +1/+0 until end of turn. It deals damage equal to its power to up to one target creature an opponent controls.

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.)

Command Tower

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

Arcane Signet

Persistent Marshstalker

This creature gets +1/+0 for each other Rat you control.
Threshold — Whenever you attack with one or more Rats, if there are seven or more cards in your graveyard, you may pay {2}{B}. If you do, return this card from your graveyard to the battlefield tapped and attacking.

Changeling Wayfinder

Changeling (This card is every creature type.)
When this creature enters, you may search your library for a basic land card, reveal it, put it into your hand, then shuffle.

Mind Stone

{T}: Add {C}.
{1}, {T}, Sacrifice this artifact: Draw a card.

Chromatic Lantern

Lands you control have "{T}: Add one mana of any color."
{T}: Add one mana of any color.

Gryff's Boon

Enchant creature
Enchanted creature gets +1/+0 and has flying.
{3}{W}: Return this card from your graveyard to the battlefield attached to target creature. Activate only as a sorcery.

The Great Henge

This spell costs {X} less to cast, where X is the greatest power among creatures you control.
{T}: Add {G}{G}. You gain 2 life.
Whenever a nontoken creature you control enters, put a +1/+1 counter on it and draw a card.

Sword of Vengeance

Equipped creature gets +2/+0 and has first strike, vigilance, trample, and haste.
Equip {3}

Ceremonial Groundbreaker

Equipped creature gets +2/+1 and has trample.
Equip Citizen {1}
Equip {3} ({3}: Attach to target creature you control. Equip only as a sorcery.)

Doran, Besieged by Time

Each creature spell you cast with toughness greater than its power costs {1} less to cast.
Whenever a creature you control attacks or blocks, it gets +X/+X until end of turn, where X is the difference between its power and toughness.

Forest

Rogue's Passage

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

Caves of Koilos

{T}: Add {C}.
{T}: Add {W} or {B}. This land deals 1 damage to you.

Farseek

Search your library for a Plains, Island, Swamp, or Mountain card, put it onto the battlefield tapped, then shuffle.

Dark Knight's Greatsword

Job select (When this Equipment enters, create a 1/1 colorless Hero creature token, then attach this to it.)
Equipped creature gets +3/+0 and is a Knight in addition to its other types.
Chaosbringer — Equip—Pay 3 life. Activate only once each turn.

Swiftfoot Boots

Equipped creature has hexproof and haste. (It can't be the target of spells or abilities your opponents control. It can attack and {T} no matter when it came under your control.)
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Scales of Shale

Affinity for Lizards (This spell costs {1} less to cast for each Lizard you control.)
Target creature gets +2/+0 and gains lifelink and indestructible until end of turn.

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."

Lightning Greaves

Equipped creature has haste and shroud. (It can't be the target of spells or abilities.)
Equip {0}

Terramorphic Expanse

{T}, Sacrifice this land: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Fake Your Own Death

Until end of turn, target creature gets +2/+0 and gains "When this creature dies, return it to the battlefield tapped under its owner's control and you create a Treasure token." (It's an artifact with "{T}, Sacrifice this token: Add one mana of any color.")

Stalactite Dagger

When this Equipment enters, create a 1/1 colorless Shapeshifter creature token with changeling. (It's every creature type.)
Equipped creature gets +1/+1 and is all creature types.
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

Gilt-Leaf's Embrace

Flash
Enchant creature
When this Aura enters, enchanted creature gains trample and indestructible until end of turn. (Damage and effects that say "destroy" don't destroy it. If its toughness is 0 or less, it still dies.)
Enchanted creature gets +2/+0.

Overgrown Tomb

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

Unbury

Choose one —
• Return target creature card from your graveyard to your hand.
• Return two target creature cards that share a creature type from your graveyard to your hand.

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.)

Evolving Wilds

Valiant Farewell

Target creature you control gets +2/+0 until end of turn. When that creature leaves the battlefield this turn, you get a boon with "When you cast your next creature spell, it perpetually gets +2/+0."
Draw a card.

Swamp

Return to Action

Until end of turn, target creature gets +1/+0 and gains lifelink and "When this creature dies, return it to the battlefield tapped under its owner's control."

Rat Colony

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

Plains

Garruk's Uprising

When this enchantment enters, if you control a creature with power 4 or greater, draw a card.
Creatures you control have trample. (Each of those creatures can deal excess combat damage to the player or planeswalker it's attacking.)
Whenever a creature you control with power 4 or greater enters, draw a card.

Shared Roots

Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.