Boreal Shelf

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

Glacial Floodplain

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

Rimewood Falls

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

Shimmerdrift Vale

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

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.)

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.)

Arctic Treeline

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

Snow-Covered Forest

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.