hmmm interesting. they showed a lot of their answers in the 3.2 patch notes.
Arcane Blast: Mana cost reduced by 12%.
Invisibility: Can no longer be interrupted by a hostile action or damage done during the 3 second fade time, however an invisible mage can still be stunned or silenced.
Empowered Fire: In addition to its existing effects, this talent now also grants a 33/67/100% chance to regain 1% of base mana each time the Ignite talent deals damage.
yes, its a huge change for mages... 3 things wooo!. less mana cost for arcane... is huge. the main reason i don't play arcane is the serious mps usage. fixing invis so i can keep casting and/or take damage and i still get my threat dump. i think heart and V will truely appreciate that. 1% base mana (32.68 mana) every 2 secconds so long as i crit once per 4 secconds. that can theoretically give 81.7 mp5, with 1 crit every 4 secconds. more realistically it will be around 70, but that is pretty massive.
there is also a ninja nerf to replenishment... if you didn't notice. instead of .25% base mana /seccond, its 1% base mana every 5 secconds. that is .25% base mana/5 less regen, or for a mage its about 8.6 mp5.
for mages, its roughly an 1.6 mana/seccond loss in manaregen... or 8mp5.
12% less mana for AB is huge too.
the one oddity here is i find it wierd how they chose to make fire more mana efficient. that extra 75 mp5 of regen also applies to ffb, so a spec that can already cast in a raid setting for almost 15 minutes before goinig oom, gets pushed over the top. i'll do the math later, but i think the 75 mp5 is enough to put ffb into an infinite cast time till oom if raid buffed. thats rediculous.