Season of Ice

+12% to Cold Damage over Time Multiplier
20% increased Effect of Chill [1]

Unpredictable Offensive is a notable passive skill.

Anointment

Blight anointment to unlock the passive:

Oil #1	Oil #2	Oil #3	Outcome
Indigo Oil	Black Oil	Golden Oil	Season of Ice	+12% to Cold Damage over Time Multiplier 20% increased Effect of Chill

Version	Changes
3.21.0	The small entry Passive Skill in the Season of Ice cluster now provides +4% to Cold Damage over Time Multiplier (previously +5%) The small Passive Skill prior to Season of Ice now providing +6% to Cold Damage over Time Multiplier (previously +5%). We've also added a third small Passive Skill to the Season of Ice cluster, which provides 20% increased Effect of Chill.
3.16.0	Unpredictable Offensive removed from the game. Existing items anointed with that passive now have Season of Ice instead.
3.11.0	Many passive skill clusters offered the same thing as other clusters, with the only differences being the location on the tree and the number of passive skills in the cluster. We also wanted to reduce the power of some clusters that were overly efficient, and increase the power of clusters that were inefficient. [Undocumented This change was not documented by any official sources. It was discovered through player testing or datamining.]^[1] Now grants 30% chance to Avoid being Stunned while Channelling (up from 20%).
3.7.0	Introduced to the game

↑ Bex_GGG (June 17, 2020). "All Notables and Keystones in Path of Exile: Harvest". Official Path of Exile forums. Retrieved November 5, 2021.