Frostfire

So I did some research. And it looks like the top dps spec for mage at 80 is: 0/53/18 At least according to the most recent Elitist Jerks post on mage theory crafting.

It's an actual elementalist build! Or at least as close to elemental as you can get with the current talent trees. I guess it's really a deep fire build with a bit of frost talents thrown on top to make frostfire bolt even more powerful.

From looking at the talents and reading a bit, it looks like frostfire bolt will do less damage than fireball, but will have god-like crits. I foresee that Viljo will have to get a bit faster with the invis/ice block. Or, heh, maybe the tanks can actually build enough threat.