Gediablo

Good post by Alvira. I especially like the part about AB-spam as much as possible being the key and every thing else is just different ways to preserve mana without gimping you mana too much. This is unlike all other specs and classes, and is essential to understand how to play arcane. I have read too many bad arcane guides praising 3xAB+1xAM+1xscorch as the BEST DPS rotation. It is not, nor is any firebuild and spec. AB spam infinitely with 40 talent points in arcane is. The best way to make the mana last longer (for me with my gear) when this isn't possible for me is to squeeze in some clusters of 3xfrostbolts now and then (4xtier6 + 2xtier5 is really awesome for this spec). I don't think the original post by Alvira emphasized the whole AB debuff management too good though. The point of using e.g 3xfrostbolts or 1xAM+1xScorch before returning to AB spam is that the mana cost of the AB spell is based on the number of AB debuffs when ending the cast, while the casttime depends on the number of buffs when starting the casting - so you can get a just 1.5 cast AB for basic manacost. The whole filler discussion is revolving around that mechanic.

Anyway to the reason I made this post - this thread needs this table:
My point here is that the percent mana cost increase of AB with a debuff is additive with Tier5 two set bonus. The extra mana costs are just added together (not multiplied) and used on the default spell cost. Basically this means that when you use Arcane power you should just spam AB, as it doesn't really matter that much if the spell cost 672 or 731 mana when you get 30% more damage for only 8.8% more mana cost.

I have raided as much as arcane as fire in TBC so far - tried all TBC raid encounters so far including Felmyst as both specs several times. Atm I'm mainly doing Sunwell, and I'm specced 40-0-21 and is able to do 2.1k dps on 6.00 min Brutallus kill (probably the worst fight for this spec). It is around 100-150 dps lower on this boss than I have been able to do on him as fire so far, but the 40-0-21 spec is MUCH better for e.g. both trash, Kalecgos and Felmyst (and most other encounters in the game). For 5 and 10 man instances no firemage will be able to keep up with my damage as 40-0-21, unless the pulls happens so fast that I cannot drink - aggro, scorch-up-time, weaker AoE, and simply lower dps than AB spam makes it impossible. This is a fact.

My impression on arcane is this: Not worth it for 25 man raids without 2xtier5 and a shadowpriest+resto/elemetalshaman in your group. You simply have to stop spamming AB too often without them. Also if you hate using gem and super mana pots on max cooldown never touch this spec. If it is unthinkable that you can ask druids for innervate on trash pulls in raids don't bother respeccing this either - you will probably wipe the raid due to slow polymorph from you sitting oom in a corner drinking (unless your guild is slow at clearing trash). On the other hand if the above isn't a problem and you know how to spam AB non-stop (doh!) this is for you. AB spam (or AE spam) is possible on pretty much all raid trash pulls in TBC, and this makes it vastly superior to fire on trash in all raids - even better dps than warlocks in this department. On bosses on farmstatus arcane is better than fire in most cases for the same reason - If the boss got below 3 million hp it is extremely doable to spam AB the entire bossfight and again fire cannot compete. In utility/survival fights the extra iceblock and not having playing with fire favors this spec to fire again. Another thing that talks for this spec is how aggressive you are with taking aggro risks. Personally I hate the thought of me wiping the raid at an encounter due to pulling aggro, which in many fights makes my fire damage a bit lower, than I know it could be. As arcane I hardly ever have to watch my aggro in raids, and can even go all out in 5 mans heroics without pulling aggro - that is unthinkable as fire.

Fire isn't useless, and in some bossfights fire is better than arcane, but the better you and your guild knows the encounters the better arcane becomes even in those fights. For some mages what makes them do their best is hugging the aggro as much as possible in a firespec, for others it is aiming to go oom as you go out of combat every pull - stick to the playstyle that suits you the best. For me it is currently arcane.