Hello. After 500+ arena games in a new world for frost mage, I'm going to change the class. Perhaps my conclusions will be useful to you:
First, Deep freeze requires 2 epic, which cannot pull out an opponent that can only be used under freezing, why not take the multifunctional shadowfury? Or a less expensive Capacitor
Secondly, if you take shadowfury, it doesn't make sense to pump the main new talent of Ice Shards even more. Which adds a small 8% compared to other classes to damage on frozen targets without working EVEN when Fingers of frost is hanging on me.
Third, considering the cost of a large number of important epic abilities for frost mage (compared to rogue) how can you spend 2 epic on cold snap (there simply won't be any left if you take at least one from another class), why not make it legendary?
The general conclusion is this: there is no chance against the classic ambush rogue in the arena, against the experienced mele, too. Frost mage loses its zest to keep enemies at a distance, it is impossible to get away and control, there is always a counteraction to this by spending less on abilities.