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Greater ice storm
wizard attack 29

area burst 5 within 20 squares

Target: each creature within this power's area of effect

Attack: Intelligence vs. Fortitude

Hit: "4d8 + Intelligence modifier cold damage, and the target is immobilized (save ends)."

Miss: "Half damage, and the target is slowed (save ends)."

Effect: "The burst creates a zone of difficult terrain that lasts until the end of the encounter."[PH:168][Dr401:74]

Greater ice storm is a daily power available to wizards at 29th level. This is a powerful ice spell. Much like meteor swarm, it blasts foes with an large area of effect storm of ice shards.

The "Class Compendium: The Arcanist" article in Dragon 401 added the evocation keyword to greater ice storm.