Target: each creature in the area of effect
Attack: Intelligence vs. Fortitude
1d8 + Intelligence modifier cold damage."
Miss: "Half damage."
The cloud lasts until the end of your next turn. Any creature that enters the cloud or starts its turn here is subject to another attack. You can dismiss the cloud as a minor action."[PH:160]
The "Class Compendium: The Arcanist" article in Dragon 401 added the evocation and zone keywords to freezing cloud, increased its initial damage, modified the effect of the zone it creates, and allowed the zone to be sustained as a minor action. The December 2011 update finalized these changes.