Manifold Mouse

Offspring {2} (You may pay an additional {2} as you cast this spell. If you do, when this creature enters, create a 1/1 token copy of it.)
At the beginning of combat on your turn, target Mouse you control gains your choice of double strike or trample until end of turn.

Veteran Guardmouse

Valiant — Whenever this creature becomes the target of a spell or ability you control for the first time each turn, it gets +1/+0 and gains first strike until end of turn. Scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Command Tower

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

Plateau

Mouse Trapper

Flash
Valiant — Whenever this creature becomes the target of a spell or ability you control for the first time each turn, tap target creature an opponent controls.

Pillarverge Pathway

Needleverge Pathway

Needleverge Pathway // Pillarverge Pathway

Arcane Signet

Mabel, Heir to Cragflame

Other Mice you control get +1/+1.
When Mabel enters, create Cragflame, a legendary colorless Equipment artifact token with "Equipped creature gets +1/+1 and has vigilance, trample, and haste" and equip {2}.

Sol Ring

Mountain

Plains

Arid Mesa

{T}, Pay 1 life, Sacrifice this land: Search your library for a Mountain or Plains card, put it onto the battlefield, then shuffle.

Seedglaive Mentor

Vigilance, haste
Valiant — Whenever this creature becomes the target of a spell or ability you control for the first time each turn, put a +1/+1 counter on it.

Steelburr Champion

Offspring {1}{W} (You may pay an additional {1}{W} as you cast this spell. If you do, when this creature enters, create a 1/1 token copy of it.)
Vigilance
Whenever an opponent casts a noncreature spell, put a +1/+1 counter on this creature.

Clifftop Retreat

This land enters tapped unless you control a Mountain or a Plains.
{T}: Add {R} or {W}.

Sundown Pass

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

Sacred Foundry

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

Rugged Prairie

{T}: Add {C}.
{R/W}, {T}: Add {R}{R}, {R}{W}, or {W}{W}.

Exotic Orchard

{T}: Add one mana of any color that a land an opponent controls could produce.

Thistledown Players

Whenever this creature attacks, untap target nonland permanent.

Secluded Courtyard

As this land 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 or activate an ability of a creature source of the chosen type.

Heartfire Hero

Valiant — Whenever this creature becomes the target of a spell or ability you control for the first time each turn, put a +1/+1 counter on it.
When this creature dies, it deals damage equal to its power to each opponent.

Spectator Seating

This land enters tapped unless you have two or more opponents.
{T}: Add {R} or {W}.

Sunbillow Verge

{T}: Add {W}.
{T}: Add {R}. Activate only if you control a Mountain or a Plains.

Whiskervale Forerunner

Valiant — Whenever this creature becomes the target of a spell or ability you control for the first time each turn, look at the top five cards of your library. You may reveal a creature card with mana value 3 or less from among them. You may put it onto the battlefield if it's your turn. If you don't put it onto the battlefield, put it into your hand. Put the rest on the bottom of your library in a random order.

Brambleguard Captain

At the beginning of combat on your turn, target creature you control gets +X/+0 until end of turn, where X is this creature's power.

Whiskerquill Scribe

Valiant — Whenever this creature becomes the target of a spell or ability you control for the first time each turn, you may discard a card. If you do, draw a card.

Sunscorched Divide

Scabland

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

Nettle Guard

Valiant — Whenever this creature becomes the target of a spell or ability you control for the first time each turn, it gets +0/+2 until end of turn.
{1}, Sacrifice this creature: Destroy target artifact or enchantment.

Emberheart Challenger

Haste
Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
Valiant — Whenever this creature becomes the target of a spell or ability you control for the first time each turn, exile the top card of your library. Until end of turn, you may play that card.

Furycalm Snarl

As this land enters, you may reveal a Mountain or Plains card from your hand. If you don't, this land enters tapped.
{T}: Add {R} or {W}.

Flowerfoot Swordmaster

Offspring {2} (You may pay an additional {2} as you cast this spell. If you do, when this creature enters, create a 1/1 token copy of it.)
Valiant — Whenever this creature becomes the target of a spell or ability you control for the first time each turn, Mice you control get +1/+0 until end of turn.

Boros Garrison

This land enters tapped.
When this land enters, return a land you control to its owner's hand.
{T}: Add {R}{W}.