It's Arcane Blast all day every day following majors
Arcane was surprising it remained relevant from super early and still is at the conclusion of the expansion, but for wrath, it does feel that eventually it's going to lose its relevance and a completely different mage spec WoTLK Gold will take over or become more complex. arcane is on the simpler side , as it has always been, unless you use Arcane Missiles.
When you get a proc aside from that, it's Arcane Blast all day every day following majors is largely dependent on performance as DPS is the most important thing that they provide and despite arcane being good early , I'm not sure if other specs will also be doing it you may see minors included in the roster , but not as much as the ability to use a stack in a way that is extremely useful and we've got the mage's normal intellect or amplify or damp and magics and table or arcane . They also have a new focus magic talent which offers another member of the raid 3% crit and of course the 33% damage across the entire raid buff arcane empowerment.
In addition, sometimes spell steal could be crucial to so arcane get some average score here in PvP. It also has more to offer than TBC with more survivability focused abilities, but it is quite squishy. However, if you decide to let it cast, you are able to eliminate players and it is anticipated to outperform arcane midway through the expansion WOW WoTLK Classic Gold and by ICC will be well ahead of the age old problem with fire that it requires.