Anyways, dunno is it an exploit or not, but arcane mage can pull an amazing dps and damage like 15k dps, when he is standing in dark zone and just spam the AB, the aura in there allows to cast with 75% less mana, so 1 ab is ca ~ 500 mana with 3 debuffs on. so just spam ab in the dark zones, then go into green one. regen mana and back into the dark. It really helps to nuke him down faster
To make it little bit clear, mage with 3 ab debuff spamm does a huge dps, but every ab is like 3k mana, so with the dark zone, its 500 mana and you can spam it and nuke its hardly -.-