Isu the Abominable

You may look at the top card of your library any time.
You may play snow lands and cast snow spells from the top of your library.
Whenever another snow permanent you control enters, you may pay {G}, {W}, or {U}. If you do, put a +1/+1 counter on Isu.

Hylda's Crown of Winter

{1}, {T}: Tap target creature. This ability costs {1} less to activate during your turn.
{3}, Sacrifice Hylda's Crown of Winter: Draw a card for each tapped creature your opponents control.

Rimewood Falls

({T}: Add {G} or {U}.)
This land enters tapped.

Counterspell

Saddled Rimestag

This creature gets +2/+2 as long as you had another creature enter the battlefield under your control this turn.

Spirit of the Aldergard

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

Frostweb Spider

Reach (This creature can block creatures with flying.)
Whenever this creature blocks a creature with flying, put a +1/+1 counter on this creature at end of combat.

Moritte of the Frost

Changeling (This card is every creature type.)
You may have Moritte enter as a copy of a permanent you control, except it's legendary and snow in addition to its other types and, if it's a creature, it enters with two additional +1/+1 counters on it and has changeling.

Growth Spiral

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

Pilfering Hawk

Flying
{S}, {T}: Draw a card, then discard a card. ({S} can be paid with one mana from a snow source.)

Iceberg Cancrix

Whenever another snow permanent you control enters, you may have target player mill two cards.

The Three Seasons

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Mill three cards.
II — Return up to two target snow permanent cards from your graveyard to your hand.
III — Choose three cards in each graveyard. Their owners shuffle those cards into their libraries.

Joint Exploration

Kicker {G} (You may pay an additional {G} as you cast this spell.)
Scry 2, then draw a card. If this spell was kicked, you may put a land card from your hand onto the battlefield.

On Thin Ice

Enchant snow land you control
When this Aura enters, exile target creature an opponent controls until this Aura leaves the battlefield.

Snow-Covered Forest

Blizzard Brawl

Choose target creature you control and target creature you don't control. If you control three or more snow permanents, the creature you control gets +1/+0 and gains indestructible until end of turn. Then those creatures fight each other. (Each deals damage equal to its power to the other.)

Faceless Haven

{T}: Add {C}.
{S}{S}{S}: This land 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.)

Sculptor of Winter

Sol Ring

Icebind Pillar

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

Winter's Rest

Enchant creature
When this Aura enters, tap enchanted creature.
As long as you control another snow permanent, enchanted creature doesn't untap during its controller's untap step.

Frostwalk Bastion

{T}: Add {C}.
{1}{S}: Until end of turn, this land becomes a 2/3 Construct artifact creature. It's still a land. ({S} can be paid with one mana from a snow source.)
Whenever this land deals combat damage to a creature, tap that creature and it doesn't untap during its controller's next untap step.

Boreal Shelf

This land enters tapped.
{T}: Add {W} or {U}.

Boreal Druid

Arcane Signet

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

Rimewind Cryomancer

{1}, {T}: Counter target activated ability. Activate only if you control four or more snow permanents. (Mana abilities can't be targeted.)

Blizzard Strix

Flash
Flying
When this creature enters, if you control another snow permanent, exile target permanent other than this creature. Return that card to the battlefield under its owner's control at the beginning of the next end step.

Ascendant Spirit

{S}{S}: This creature becomes a Spirit Warrior with base power and toughness 2/3.
{S}{S}{S}: If this creature 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 this creature 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."

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.)

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.)

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.)

Cultivate

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.

Icebreaker Kraken

Affinity for snow lands (This spell costs {1} less to cast for each snow land you control.)
When this creature enters, 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 this creature to its owner's hand.

Hylda of the Icy Crown

Whenever you tap an untapped creature an opponent controls, you may pay {1}. When you do, choose one —
• Create a 4/4 white and blue Elemental creature token.
• Put a +1/+1 counter on each creature you control.
• Scry 2, then draw a card.

Replicating Ring

{T}: Add one mana of any color.
At the beginning of your upkeep, put a night counter on this artifact. Then if it has eight or more night counters on it, remove all of them and create eight colorless snow artifact tokens named Replicated Ring with "{T}: Add one mana of any color."

Thespian's Stage

{T}: Add {C}.
{2}, {T}: This land becomes a copy of target land, except it has this ability.

Glittering Frost

Enchant land
Enchanted land is snow.
Whenever enchanted land is tapped for mana, its controller adds an additional one mana of any color.

Mouth of Ronom

{T}: Add {C}.
{4}{S}, {T}, Sacrifice this land: It deals 4 damage to target creature. ({S} can be paid with one mana from a snow source.)

Storvald, Frost Giant Jarl

Ward {3}
Other creatures you control have ward {3}.
Whenever Storvald enters or attacks, choose one or both —
• Target creature has base power and toughness 7/7 until end of turn.
• Target creature has base power and toughness 1/1 until end of turn.

Arcum's Astrolabe

({S} can be paid with one mana from a snow source.)
When this artifact enters, draw a card.
{1}, {T}: Add one mana of any color.

Plunge into Winter

Tap up to one target creature. Scry 1, then draw a card.

Path to Exile

Exile target creature. Its controller may search their library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Boreal Outrider

Whenever you cast a creature spell, if {S} of any of that spell's colors was spent to cast it, that creature enters with an additional +1/+1 counter on it. ({S} is mana from a snow source.)

Glacial Revelation

Reveal the top six cards of your library. You may put any number of snow permanent cards from among them into your hand. Put the rest into your graveyard.

Azusa, Lost but Seeking

You may play two additional lands on each of your turns.

Gelid Shackles

Enchant creature
Enchanted creature can't block, and its activated abilities can't be activated.
{S}: Enchanted creature gains defender until end of turn. ({S} can be paid with one mana from a snow source.)

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.

Farseek

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

Icehide Troll

{S}{S}: This creature gets +2/+0 and gains indestructible until end of turn. Tap it. (Damage and effects that say "destroy" don't destroy it. {S} can be paid with one mana from a snow source.)

Arctic Flats

This land enters tapped.
{T}: Add {G} or {W}.

Frostpeak Yeti

{1}{S}: This creature can't be blocked this turn. ({S} can be paid with one mana from a snow source.)

Glacial Floodplain

({T}: Add {W} or {U}.)
This land enters tapped.

Ohran Frostfang

Attacking creatures you control have deathtouch.
Whenever a creature you control deals combat damage to a player, draw a card.

Rime Tender

{T}: Untap another target snow permanent.

Icehide Golem

({S} can be paid with one mana from a snow source.)

Berg Strider

When this creature enters, tap target artifact or creature an opponent controls. If {S} was spent to cast this spell, that permanent doesn't untap during its controller's next untap step. ({S} is mana from a snow source.)

Into the North

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

Shimmerdrift Vale

This land enters tapped.
As this land enters, choose a color.
{T}: Add one mana of the chosen color.

Spara's Headquarters

({T}: Add {G}, {W}, or {U}.)
This land enters tapped.
Cycling {3} ({3}, Discard this card: Draw a card.)

Ice-Fang Coatl

Flash
Flying
When this creature enters, draw a card.
This creature has deathtouch as long as you control at least three other snow permanents.

Scrying Sheets

{T}: Add {C}.
{1}{S}, {T}: Look at the top card of your library. If that card is snow, you may reveal it and put it into your hand. ({S} can be paid with one mana from a snow source.)

Coldsteel Heart

This artifact enters tapped.
As this artifact enters, choose a color.
{T}: Add one mana of the chosen color.

Rimewind Taskmage

{1}, {T}: You may tap or untap target permanent. Activate only if you control four or more snow permanents.

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.

Kodama's Reach

Succumb to the Cold

Tap one or two target creatures an opponent controls. Put a stun counter on each of them. (If a permanent with a stun counter would become untapped, remove one from it instead.)

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.)

Abominable Treefolk

Trample
Abominable Treefolk's power and toughness are each equal to the number of snow permanents you control.
When this creature enters, tap target creature an opponent controls. That creature doesn't untap during its controller's next untap step.

Snow-Covered Plains

Blessing of Frost

Distribute X +1/+1 counters among any number of creatures you control, where X is the amount of {S} spent to cast this spell. Then draw a card for each creature you control with power 4 or greater.

Snow-Covered Island

Freeze in Place

Tap target creature an opponent controls and put three stun counters on it. Scry 2. (If a permanent with a stun counter would become untapped, remove one from it instead.)

Swords to Plowshares

Exile target creature. Its controller gains life equal to its power.

Command Tower

Arctic Treeline

({T}: Add {G} or {W}.)
This land enters tapped.

Rampant Growth

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