Marit Lage's Slumber

Whenever Marit Lage's Slumber or another snow permanent enters the battlefield under your control, 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.

Frost Augur

{S}, {T}: Look at the top card of your library. If it's a snow card, you may reveal it and put it into your hand. ({S} can be paid with one mana from a snow source.)

Boreal Shelf

Boreal Shelf enters the battlefield tapped.
{T}: Add {W} or {U}.

Icebind Pillar

{S}, {T}: Tap target artifact or creature. ({S} can be paid with one mana from a snow source.)

Glacial Floodplain

({T}: Add {W} or {U}.)
Glacial Floodplain enters the battlefield tapped.

Search for Glory

Search your library for a snow permanent card, a legendary card, or a Saga card, reveal it, put it into your hand, then shuffle. You gain 1 life for each {S} spent to cast this spell. ({S} is mana from a snow source.)

Snow-Covered Plains

Faceless Haven

{T}: Add {C}.
{S}{S}{S}: Faceless Haven becomes a 4/3 creature with vigilance and all creature types until end of turn. It's still a land. ({S} can be paid with one mana from a snow source.)

On Thin Ice

Enchant snow land you control
When On Thin Ice enters the battlefield, exile target creature an opponent controls until On Thin Ice leaves the battlefield.

Icebreaker Kraken

This spell costs {1} less to cast for each snow land you control.
When Icebreaker Kraken enters the battlefield, artifacts and creatures target opponent controls don't untap during that player's next untap step.
Return three snow lands you control to their owner's hand: Return Icebreaker Kraken to its owner's hand.

Squall Drifter

Ascendant Spirit

{S}{S}: Ascendant Spirit becomes a Spirit Warrior with base power and toughness 2/3.
{S}{S}{S}: If Ascendant Spirit is a Warrior, put a flying counter on it and it becomes a Spirit Warrior Angel with base power and toughness 4/4.
{S}{S}{S}{S}: If Ascendant Spirit is an Angel, put two +1/+1 counters on it and it gains "Whenever this creature deals combat damage to a player, draw a card."

Snow-Covered Island

Avalanche Caller

{2}: Target snow land you control becomes a 4/4 Elemental creature with hexproof and haste until end of turn. It's still a land. (A creature with hexproof can't be the target of spells or abilities your opponents control.)

Graven Lore

Scry X, where X is the amount of {S} spent to cast this spell, then draw three cards. ({S} is mana from a snow source.)