Rimefeather Owl

Flying
Rimefeather Owl's power and toughness are each equal to the number of snow permanents on the battlefield.
{1}{S}: Put an ice counter on target permanent.
Permanents with ice counters on them are snow.

Barbarian Guides

{2}{R}, {T}: Choose a land type. Target creature you control gains snow landwalk of the chosen type until end of turn. Return that creature to its owner's hand at the beginning of the next end step. (It can't be blocked as long as defending player controls a snow land of that type.)

Balduvian Conjurer

{T}: Target snow land becomes a 2/2 creature until end of turn. It's still a land.

Freyalise's Radiance

Cumulative upkeep {2} (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)
Snow permanents don't untap during their controllers' untap steps.

Balduvian Frostwaker

{U}, {T}: Target snow land becomes a 2/2 blue Elemental creature with flying. It's still a land.

Arcum's Sleigh

{2}, {T}: Target creature gains vigilance until end of turn. Activate only during combat and only if defending player controls a snow land.

Legions of Lim-Dûl

Snow swampwalk (This creature can't be blocked as long as defending player controls a snow Swamp.)

Thermokarst

Destroy target land. If that land was a snow land, you gain 1 life.

Arcum's Whistle

{3}, {T}: Choose target non-Wall creature the active player has controlled continuously since the beginning of the turn. That player may pay {X}, where X is that mana value. If they don't pay, the creature attacks this turn if able, and at the beginning of the next end step, destroy it if it didn't attack this turn. Activate only before attackers are declared.

Thermal Flux

Choose one —
• Target nonsnow permanent becomes snow until end of turn.
• Target snow permanent isn't snow until end of turn.
Draw a card at the beginning of the next turn's upkeep.

Cold Snap

Cumulative upkeep {2} (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)
At the beginning of each player's upkeep, Cold Snap deals damage to that player equal to the number of snow lands they control.

Arctic Foxes

Arctic Foxes can't be blocked by creatures with power 2 or greater as long as defending player controls a snow land.

Melting

Morophon, the Boundless

Changeling (This card is every creature type.)
As Morophon, the Boundless enters, choose a creature type.
Spells of the chosen type you cast cost {W}{U}{B}{R}{G} less to cast. This effect reduces only the amount of colored mana you pay.
Other creatures you control of the chosen type get +1/+1.

Ronom Hulk

Protection from snow
Cumulative upkeep {1} (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)

Avalanche

Icequake

Destroy target land. If that land was a snow land, Icequake deals 1 damage to that land's controller.

Rime Dryad

Snow forestwalk (This creature can't be blocked as long as defending player controls a snow Forest.)

Arcum's Weathervane

{2}, {T}: Target snow land is no longer snow.
{2}, {T}: Target nonsnow basic land becomes snow.