I'll walk through the tree of talents from Emily's blog

If you are aware that tanks won't be able to keep WoTLK Gold aggro on the majority of mobs, and they've just pulled an enormous pulling, you can use the mirror images and go to hammer on AOE and be confident that you're not likely to pull off a girl. 

In this article, I'll walk through the tree of talents and the various changes that have been made from TPC to Wrath Lich King for each of the various arcane abilities, and also various arcane abilities that you can take advantage of. First, I'll discuss the most significant change to arcane, which is that there's been a change made to the Arcane Blast and the buff it grants.

Before and after TBC you boost the cost of mana for arcane blasts and decrease the time required to cast the Arcane Blast. What it does is boost the damage of all arcane spells aswell in the mana cost of Arcane Blast. This effect can be stacked at up to buy WoTLK Classic Gold times and last for 6 seconds or until the arcane spell is utilized.