Target: each creature in the area of effect
Attack: Intelligence vs. Reflex
Hit: "1d6 + Intelligence modifier cold damage, and the target falls prone."
The power's area is difficult terrain until the end of your next turn. You can end this effect as a minor action."[PH:160][Dr401:54][U:12/2011]
Icy terrain is an encounter power available to wizards at 1st level.
The "Class Compendium: The Arcanist" article in Dragon 401 added the evocation and zone keywords to icy terrain. The December 2011 update finalized these changes.