What is a frost mages primary DPS spell? Their blizzard? If so that will suck for 3boxing due to being a targeted and channeled spell.

For leveling my AE group I went with a pally for tanking (spec'd holy) and two arcane mages... Works great, there's some lower level examples of their sticking power in the video's forum (Look for Team Doublemint).

I'll grab some updated footage this weekend and show some mid-30's AE grinding and the agro I hold even better now ! Of course as I level the mages are reaching into the fire tree now, and becoming more of a force to be dealt with... at some point I'll switch the paladin to Prot/Holy but it wont be until I can reach Holy Shield.