Icy terrain
wizard attack 1
Target: each creature in the area of effect
Attack: Intelligence vs. Reflex
Hit: "1d6 + Intelligence modifier cold damage, and the target falls prone."
Effect: "The burst creates a zone that lasts until the end of your next turn or until you end it as a minor action. The ground of the zone is difficult terrain. 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.