Arcum's Astrolabe

({S} can be paid with one mana from a snow source.)
When Arcum's Astrolabe enters, draw a card.
{1}, {T}: Add one mana of any color.

Stream of Thought

Target player mills four cards. You shuffle up to four cards from your graveyard into your library.
Replicate {2}{U}{U} (When you cast this spell, copy it for each time you paid its replicate cost. You may choose new targets for the copies.)

Vapor Snag

Return target creature to its owner's hand. Its controller loses 1 life.

Jace's Erasure

Whenever you draw a card, you may have target player mill a card.

Winter's Rest

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

Snow-Covered Island

Ghostly Flicker

Exile two target artifacts, creatures, and/or lands you control, then return those cards to the battlefield under your control.

Spore Frog

Sacrifice Spore Frog: Prevent all combat damage that would be dealt this turn.

Snow-Covered Forest

Brainstorm

Draw three cards, then put two cards from your hand on top of your library in any order.

Boreal Druid

Rime Tender

{T}: Untap another target snow permanent.

String of Disappearances

Return target creature to its owner's hand. Then that creature's controller may pay {U}{U}. If the player does, they may copy this spell and may choose a new target for that copy.

Iceberg Cancrix

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