Target: each enemy within this power's area of effect
Attack: Charisma vs. Fortitude
Hit: "1d10 + Charisma modifier cold damage."
Miss: "Half damage."
Effect: "The burst creates a zone of hindering frost that lasts until the end of your next turn. When any enemy enters the zone or starts its turn there, it is slowed .
If the enemy is marked by you, it is immobilized until the end of your next turn instead."
Prior to the March 2010 update, frost of Letherna had an unspecified slow duration that could be interprted to lead to indefinite immobilization. The March 2010 update specified a duration for the power's slow effect, and removed its immobilization.