Frost Nova

You might want to note that Mobs will always try to attack something. So if you frost nova them and you're then out of reach they'll try and attack something else unfriendly, in my case it was the level 17 Warlock I was twinking through Deadmines that had decided to stand in the middle of the group of mobs I was aoe-ing... Not a good sight. This is probably one of the few cases in which mobs will ignore their agro-metres.

actually it doesnt say automatic on first crit. it says "Increased the chance Frozen effects are broken when the target is critically struck by a spell." and after testing First crit does not break Nova automaticaly. I cast Frost Nova and then frostbolt(crit), Ice lance(crit), ice lance(crit) before the nova broke. The nurf was not the automatic break but the cummlitive modifier that determins wether the snare breaks or not. For example: first crit has 40% to break. next crit has 60% next crit has 80% to break etc. (This is not the actual math just an aesthetic example)

This is one of the most important spells in the mage's selection, as mages are "clothies" and as such, MUST avoid melee combat. This spell allows that.

It is also the reason that mages are very good at defending in WSG, as they can stop several enemies in the flag room, for the mage's teammates to destroy.