The Frost debuff itself is not a form of CC and hence cannot be cleansed by items or abilities that remove CC. Permafrost, however, is CC and can be removed.
Frost cannot be applied to any target affected by Permafrost until 3 seconds after the Permafrost debuff expires. Due to this, Permafrost is the only of Sejuani's abilities that do not apply Frost.
COST: 100 Mana
COOLDOWN: 130 / 115 / 100
Active: Sejuani throws her frost-forged bola in a line. If the bola hits an enemy champion, it shatters, stunning the target and nearby enemies for a duration. If the bola reaches its maximum range, it shatters and slows enemies by 90% instead for the same duration. All enemies in the shatter area take magic damage.