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

{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.)

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.)

{4}{S}{S}: Monstrosity 2. (If this creature isn't monstrous, put two +1/+1 counters on it and it becomes monstrous. {S} can be paid with one mana from a snow source.) As long as this creature is monstrous, it has flying.

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

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.

This creature doesn't untap during your untap step. {1}{S}: Untap this creature. ({S} can be paid with one mana from a snow source.)

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.

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