With 3 mages I'd surely take Imp Frost Nova ... That bound on round robin(or using a cast sequence macro), and yer clothies are a bit more save from melee harm

I would spend no points on Wand Spec or imp arcane missiles, just to get the imp frost nova...

But that's just me .. Had it on my lvl 38 maxed out twink mage and it owned so hard when aoe'ing, or 1 v 1's (lost duels, won fights, but pvp is what matters then )