Winter's Chill

From wow.incgamers.com

Talent: Winter's Chill
Effect: Gives your Frost damage spells a a % chance to apply the Winter's Chill effect, which increases the chance a Frost spell will critically hit the target by 2% for 15 sec. Stacks up to 5 times.
Statistics: Rank 1 = 20%, Rank 2 = 40%, Rank 3 = 60%, Rank 4 = 80%, Rank 5 = 100%.