Snow-Covered Mountain

Assimilation Aegis

When Assimilation Aegis enters, exile up to one target creature until Assimilation Aegis leaves the battlefield.
Whenever Assimilation Aegis becomes attached to a creature, for as long as Assimilation Aegis remains attached to it, that creature becomes a copy of a creature card exiled with Assimilation Aegis.
Equip {2}

Draco

Domain — This spell costs {2} less to cast for each basic land type among lands you control.
Flying
Domain — At the beginning of your upkeep, sacrifice Draco unless you pay {10}. This cost is reduced by {2} for each basic land type among lands you control.

Marit Lage's Slumber

Whenever Marit Lage's Slumber or another snow permanent you control enters, scry 1.
At the beginning of your upkeep, if you control ten or more snow permanents, sacrifice Marit Lage's Slumber. If you do, create Marit Lage, a legendary 20/20 black Avatar creature token with flying and indestructible.

Rampant Growth

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

Snow-Covered Swamp

Llanowar Scout

{T}: You may put a land card from your hand onto the battlefield.

Snow-Covered Island

Spirit of the Aldergard

When Spirit of the Aldergard enters, search your library for a snow land card, reveal it, put it into your hand, then shuffle.
Spirit of the Aldergard gets +1/+0 for each other snow permanent you control.

Mirrorpool

Mirrorpool enters tapped.
{T}: Add {C}.
{2}{C}, {T}, Sacrifice Mirrorpool: Copy target instant or sorcery spell you control. You may choose new targets for the copy.
{4}{C}, {T}, Sacrifice Mirrorpool: Create a token that's a copy of target creature you control.

Forest

Snow-Covered Plains

Growth Spiral

Draw a card. You may put a land card from your hand onto the battlefield.

Murasa Rootgrazer

Vigilance
{T}: You may put a basic land card from your hand onto the battlefield.
{T}: Return target basic land you control to its owner's hand.

Echoing Equation

Choose target creature you control. Each other creature you control becomes a copy of it until end of turn, except those creatures aren't legendary.

Augmenter Pugilist

Trample
As long as you control eight or more lands, Augmenter Pugilist gets +5/+5.

Augmenter Pugilist // Echoing Equation

Rimewood Falls

({T}: Add {G} or {U}.)
Rimewood Falls enters tapped.

Snow-Covered Forest

Arctic Treeline

({T}: Add {G} or {W}.)
Arctic Treeline enters tapped.

Alpine Meadow

({T}: Add {R} or {W}.)
Alpine Meadow enters tapped.

Cackling Counterpart

Create a token that's a copy of target creature you control.
Flashback {5}{U}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Dark Depths

Dark Depths enters with ten ice counters on it.
{3}: Remove an ice counter from Dark Depths.
When Dark Depths has no ice counters on it, sacrifice it. If you do, create Marit Lage, a legendary 20/20 black Avatar creature token with flying and indestructible.

Highland Forest

({T}: Add {R} or {G}.)
Highland Forest enters tapped.

Highland Weald

Highland Weald enters tapped.
{T}: Add {R} or {G}.

Urban Evolution

Draw three cards. You may play an additional land this turn.

Niv-Mizzet, Supreme

Flying, hexproof from monocolored
Each instant and sorcery card in your graveyard that's exactly two colors has jump-start. (You may cast that card from your graveyard by discarding a card in addition to paying its other costs. Then exile it.)

Snow-Covered Wastes

Quasiduplicate

Create a token that's a copy of target creature you control.
Jump-start (You may cast this card from your graveyard by discarding a card in addition to paying its other costs. Then exile this card.)

Dragonmaster Outcast

At the beginning of your upkeep, if you control six or more lands, create a 5/5 red Dragon creature token with flying.