Improved Blizzard is a Mage talent that adds a chill effect to the [Blizzard] spell, which slows opponent movement speed for one and a half seconds. This talent is used primarily for aoe, and can be quite useful wherever one wishes to snare a large number of enemies all at once.
Tips and tricks[]
At max rank, Blizzard will be one of the mage's strongest snare spells, matching the 50% of [Cone of Cold]. These snare effects do not stack; if Cone of Cold is in effect (with more than 1.5 sec left), the snare from Blizzard will not overwrite it. [citation needed]
Improved Blizzard makes the Blizzard spell an effective snare, but at a large mana cost. This chill can proc [Frostbite], [Brain Freeze] and, for most important, [Fingers of Frost]. Since the snare is reapplied every time it hits (which is often) Fingers of Frost will proc often, making Frost mage AoE devastrating when coupled with [Shatter].
Patch 3.0.8 (2009-01-20): The snaring effect has been reduced to 20/40/50%.
Patch 1.3.0 (2005-03-07): Chill duration reduced to 1.5 seconds (4.5 seconds w/ [Permafrost]) and refreshes with each damage tick rather than at the beginning of the spell. In addition, a target that resists the damage will also resist the chill effect.
[Blizzard]
[Cone of Cold]. These snare effects do not stack; if Cone of Cold is in effect (with more than 1.5 sec left), the snare from Blizzard will not overwrite it. [citation needed]
[Frostbite], 
[Brain Freeze] and, for most important, 
[Fingers of Frost]. Since the snare is reapplied every time it hits (which is often) Fingers of Frost will proc often, making Frost mage AoE devastrating when coupled with 
[Shatter].
Patch 4.0.1 (2010-10-12): Removed. 
