Best mage build is 31 Arcane/20 Fire. Listen to this and listen to it closely:
Instant Arcane Explosion combined with a good healer turns any "instance" intio a "nuisance."
Sunken Temple with a 52-60 mage is a fucking joke with Instant Arcane Explosion. A MUST-HAVE no matter what build you do
Cosmos reports my Damage Per Second to be around 1500-2500 when I do Instant Arcane Explosion in Sunken Temple. It's incredible.