Mage Haste (could be interesting for other casters)
OK so I have been playing with various gear combinations lately to try to see what would give me the best boost to my dps in the short and long term (damn you Nanika and your wowdigger :D ). And whatever theorycrafting tools I have used, I keep coming to the conclusion that the spellhaste gear was superior. And interesting enough, the better the rest of my gear was, the better the spellhaste pieces looked (e.g. when choosing between the haste shoulders from ZA and the mantle of the elven kings, at my current gear, the two sets are roughly equivalent. But after 2.4 comes out and I swap out my spellfire set for badge gear + belt of blasting, the haste shoulders are giving ~10 dps more than the elven king after I adjust the gems in each to be at the spellhit cap) I was talking with Nanika and she was expressing disbelief that spellhaste is really all that. So I decided to do a bit of rough modelling of my own to see what makes sense. Looking at a 3 minute fight which allows for 1 icy veins use (20% haste for 20 sec, 3 min cooldown) and assuming 0.1 sec latency I got the following: 8 Scorch casts (2 initial and classic 8xFB 1xscorch pattern) 56 Fireball casts Now at my current haste level (75 - badge bracers, OH, ZA shoulders) I get the following in the same 3 minutes: 8 Scorch casts (2 initial and 9xFB 1x scorch pattern) 58 Fireball casts That is an extra 2 fireballs per 3 minutes. At an average fireball damage of 3300 self buffed that is 36.7 dps from spellhaste. If instead we had put those points into spelldamage, it would make the average fireball hit for ~3400. 100 dam/FB *56 FB/180 sec = 31.1 dps from equivalent spelldam budget. Ths is a little back of the envelope, but you can see that spellhaste does indeed benefit overall dps more per point than spelldam. There are a few caveats: 1) Spellhaste does not increase DPM of your spells (unlike spellcrit and spelldam). In fact it increases your mana consumption rate. So if you find yourself watching anxiously for your pot and gem cooldowns, then spellhaste is probably a poor choice for that fight. 2) Spellhaste does not lower the GCD (at least until 2.4). This means that instant casts and 1.5s cast spells gain nothing from spellhaste. Dots do not tick faster with spellhaste either. This means that for now, spellhaste is best for fire mage (not arcane) and maybe destro locks depending upon their mix of SB's and dots. Aff locks and SPs will see some benefit in 2.4, but it is more complicated given the cooldowns within their spell rotations. Cooldowns are not affected by spellhaste. 3) You will only really see the benefits of spellhaste in a fight where you are chaincasting. The more things you do besides chain casting fireballs (moving, decursing, casting fireward, looking for a new target) the less valuable it is going to be to you in that fight. 4) You need to adjust your spell rotations to take advantage of spellhaste. Doing this exercise I realized that I should be doing 9xFB 1xSc instead of 8xFB when wearing my normal boss gear (or better yet just letting Terraa scorch because he is so good at it j/k). 5) You will see a bigger bang from spellhaste the better the rest of your gear is. Just imagine that the average fireball was hitting for 3600. In 3 min that would be 7200 extra damage from haste or 40 dps, vs the same 31 dps if the item points hs been spent on spelldam. What this means is when choosing gear, spellhaste is good, but it is important to get a balanced mix of stats.

Hasted AE in 2.4
Well one thing that I am really looking forward to in 2.4 is AE spam. They are raising the damage cap by ~50% so stacking crit and wading into a pile of mobs on your prot pally should be fun. Also with 2.4, spellhaste (IV, Heroism) will affect the GCD. So I am looking at 1.2 sec AE spam with my current gear. Yummy. And if you are interested -- 248 is the magic spellhaste cap to get 1 sec GCD under heroism.

Good stuff about spell haste, I'll definitely keep an eye open for spell haste gear. And yeah, the AE damage cap increase hasn't received a lot of attention, but it seems like a huge change to me. On fights like HAS and Tidewalker, this is approximately 50% damage increase on the adds. It's good to see Blizzard is making efforts to improve mage AoE.

Just soemthing i noticed: in your equation you neglected to factor in crits and the resulting ignite damage from having spell damage rather than spell haste. Also spell damage would be better when you use combustion. Blizz tends to make the ilvl of stuff equal if they give the same dps unless you have a unproportional amount of stamina (see Belt of Blasting)

for a moonkin, straight starfire spam only makes sense with full T6-lvl gear. then you stack haste and it's good. for T5+ lvl gear, in 2.4 some haste can still be useful, but less so than for a chain-long-casting class, because of our instants. a quick calculation by someone suggested a guileline that your buffed spell dmg - haste should be ~ 1200. so if you buffed dmg is 1300, then you should have 100 haste.

Actually Kyt I didn't. For ease of calculations I used 3300 which was the damage of an average fireball with my gear. This is a weighted average of the hits and crits given my crit and spellhit chance and assumng that all of the ignite damage is applied. I wasn't wanting to costruct a comprehensive model, but to get a sense of why haste looks so good when you plug it into the myriad of spreadsheets out there. But defintely thanks for humoring me and reading my math treatise :) ilevel gear may all be "equal" in budget, but they are not all equally good for all situations. I like to stack crit for AOE fights (at the expense of both spelldam since the coeff. on AE is 0.17 and spellhit because we often AoE lower lvl adds). For boss fights it is important to max spellhit. It looks like spellhaste is goodfor some bossfights as well. I also like to have a spellhit piece or 2 I can swap out if I am in a group with a shammy. And of course sometimes the item budget is spent on stats like stam but that can be good to swap in for fights like Naj :) Ave

I've been trying to add more haste in my T6 set as of late, currently I have about 56 on my final set. The problem I've been finding, as I said to Ave earlier, is that in general you don't trade spell haste for spell damage, you trade it for spell hit and crit. While haste adds more dps then crit does, hit remains the best stat to get when under the cap. The other issue being that T6 is non-negotiable for fire mages, because of the 4 piece set bonus.