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.

({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.

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.)

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

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.