Hi, so i started to level up my mage, reached 20 level, get blizzard improved combined with permafrost and..... yep it's not working with it. Please prove me if im wrong, but improved blizzard is chill effect, and permafrost is increasing slow reduce + increasing chill effect. It's very disturbing the expirience from mage. Aswell now im consider it doesn't work with any chill effect.
To be sure there is comments from wowhead and 16th comment include information from patch 1.12.0
http://www.wowhead.com/spell=10/blizzard#comments