Hmmm. But let's say its a "short" enough fight such that even gemmed with +dmg gems instead of int/spirit, you can finish the fight spamming AB all the way as well. Yes, you still have to evocate,gem, and pot. But you can spam AB the whole fight without gemming for int/spirit. Then why would it be higher DPS?

The frequency of ABs being cast would be the same. But the damage done by the mage with a set gemmed for damage should be higher because his set is gemmed for damage rather than for int/spirit.

So, for example. This particular raid boss fight. It involves the arcane mage casting a total of 40 arcane blasts, eat gem twice, drink mana pot twice, and evocate once.

Now, assuming that even when gemmed for +dmg, the mage can still spam AB and hence cast that 40 arcane blasts without running out of mana. Then, it should be higher damage right? Cos his average AB will be a higher range than the arcane mage that gemmed for int/spirit.

I'm a bit uncomfortable with the examples you're using for comparison. Your base example appears to be an ungemmed DPS set, in which you can take down a raid boss without running out of mana (which in itself is unlikely). After this, you compare the dps increase from gemming from +dmg than +int.

However, the way I see it, broadly speaking for most fights, even if they are "short", it should actually be a comparison between:

(a) Arcane mage gemmed for +dmg [at cost of mana pool], casting 40 ABs, eat gem x2, drink mana pot x2, evocate
vs
(b) Arcane mage gemmed for +int, casting 40 ABs, Flame Cap x2 (in place of gem CD), destro pot x2, evocate if necessary.

In these cases, the dps increase doesn't look as obvious for case (a). Besides, any shorter fight and you'd be talking about trash mobs.

Most of the encounters in MH/BT are unusually short. Do we have any reason to believe that Brutallus isn't on the short end rather than the long? Kalecgos seems to be 6-7 minutes for most guilds. Felmyst is a 10-minute enrage. The twin eredars, from my initial impressions, are not a short fight. M'uru has at least two phases, which suggests that it's not likely to be over in 4 minutes. And it would surprise me enormously if Kil'Jaeden was not a long encounter.

To me, Brutallus seems to be about as short an encounter as you're going to get in Sunwell. Of course, several of these fights will become shorter once raids out-gear them, but so what? Presumably progression is our focus, not farming.

And as has been pointed out, any fight where you have to evocate, int gems will out-do +damage gems. This is because you do not do any damage while evocating. The mage who gems int will cast more blasts than the mage who gems +damage.

For 40/0/21

How good is 3 * Frostbolt + 1 * AB for low mana rotation. I can't find any simulator for do math for me.
With 2*t5
Both got almoust same spell effiency. (3s*1.06 cast and 2.5 cast * 1.2)
Arcane blast got better base damage(*1.2), higher crit chance, lower base cost(in this case 195*1.2), faster cast(one debuff stack) and lower threat.
Frostbolt got better crit multplier.
So is 3*Fb + 1*AB is better than frostbolt spam for manasaving purposes?

Lost and Pitbuller, you should both be asking your questions in this thread.

(Briefly - there are no rotations. Keep the AB debuff stacked and cast AB when you have the mana for it and frostbolt when you don't. And deep fire is entirely competitive with and certainly easier and less demanding of raid synergies than arcane. It will out-damage arcane on longer fights.)

To state it again (as has been done a ton of times in previous threads), 40/0/21 is perfectly viable for Sunwell provided you have 2pc T5. Depending on group comp and debuffs it's at least competitive if not better than deep fire. But once you have access to Sunwell gear in every slot (say, Twins+), the sheer stats difference from Sunwell gear versus T5 pretty much puts 2/47/11+1 back on top. But presently as we're only just starting to have access to those levels of gear, it's disingenuous to call either spec "better" - it depends heavily on you, your guild, and your playstyle.

Can we just make a "How do I shot arcane???" thread for these kind of questions rather than turning every Mage thread into a massive Arcane derailment? I actually can't see a single question here relating to Arcane specs that hasn't been answered in the other mage threads.

The mana per 5 is horrid. Don't use it, and it caps at 20 stacks.

The fact that Skull doesn't stack anymore with other trinkets really interests me in what would be the best trinket combo in game now. I see on the armory that Manly still has the Skull/Hex combo, but is the use of Serpent-Coil Braid at the cost of a Flame Cap worth it to have the haste and extra damage at the same time? Also, assuming the use of Skull/Hex still, would it be better to use Skull during IV or use it after IV+Hex?

Last thing, while looking at some of the Nihilum mages on the armory i saw Darmor with a not so textbook spec.
Talent Calculator - World of Warcraft
Would those few dropped points in fire actually be outweighed by the use of 2 IVs back to back?

Seriously, read the existing threads. 0/40/21 is discussed in them.

Skull pulls way ahead when using Flame caps and Destruction potions. My understanding at least is to combine Flame Cap/Hex/Combustion, then Skull/Destropot/IV for the second half the Flame Cap. Ideally all with a BLust as well.

However, if the fight doesn't allow you to use a Flamecap, SCB pulls ahead.