Two-fisted Death
The central question for a mage asking build advice is: fire or frost? Arcane has its adherents—mages anxious that their spells not be resisted in PvP and mages who can’t control their threat any other way—but, because the arcane tree can’t compete for damage output, and damage is a major part of a mage’s utility, most mages opt for fire or frost. So which do you want?
Short answer: fire for solo play and PvP, frost for group PvE.
This is largely a function of damage. Burst damage from fire is enormous; frost can’t possibly compete for raw dps. PvP is all about burst damage, and even in solo PvE you’re generally better off with the quick kill. In a group, however, massive damage output will grab aggro, leading to your sudden demise. When going balls-out for damage is not a viable option, the fringe benefits of frost look a lot more appealing:
1. Superior aggro control. Not only does frost generate less dps, and thus less threat, but damage output is more even, avoiding the hideous threat spikes of a fire crit. And if you’re a naughty mage and grab aggro anyway, Ice Block can save your sorry butt.
2. What frost loses in dps it gains in superior dpm, vital for long boss fights.
3. Runners are controlled, because spamming Frostbolt applies a continuing chill effect.
You might feel this answer is too simplistic. You’d be right. The fire/frost rule of thumb needs some important qualifications.
First, frost doesn’t really come into its own until level 30 or so, when you can assemble the Ice Shards-Frostbite-Shatter combination that forms the backbone of frost builds. Until then, you’ll probably want fire talents regardless of your ultimate intentions. Second, frost allows a very specialized build designed for rapid grinding of xp, combining chill effects with AoEs to kill dozens of mobs at once. Unfortunately, the build is lousy for anything else, but if all you care about is reaching level 60-70-80 as soon as possible, AoE frost farming is the way to go.