It's generally accepted that you should get Helm/Shoulders/Pants/Gloves boomkin tier, and Chest resto off-piece. Having the base haste on the chest makes it the better option, and still outplays the mastery gain.

You should make sure a few settings on WrathCalcs are changed before you think about your DPS.

- since you aren't using the Glyph of Starsurge, make sure Starfall is set to "on cooldown" rather than "during Lunar". Also, right above that box is a blue box called "Cast Delay" - set that to your latency (default value is 0.05).
- ensure all the buffs/debuffs your raid applies is mimicked by the settings on WrathCalcs, a lot of people tend to just turn everything to "true" instead of changing the values.

Other than that, I can't really think why WrathCalcs would be reporting a higher-than-average number. Ultraxion is a squirly because of the Hour of Twilight, and having to shift out of the realm is a good 1-2k DPS loss over the entire fight, depending on how early you press the button. And yeah, Owlkin Frenzy doesn't work at all on Ultraxion, so WrathCalcs will be buffing the DPS a little over from that.

I've been running WrathCalc sims nonstop for two days. Every configuration that I use wants me to reforge into Crit, not Mastery. Generally, reforge into haste without question, make sure hit cap is reached and breached, but then... In the stat priority in the OP it claims that Crit is our weakest stat, however, after finishing the haste/hit/spirit reforges, WC always shows a DPS boost from reforging into crit over mastery. I've seen one other post where someone noticed this as well (on simulationcraft, i think) but found no answer, and so maybe it bears discussing.

I'm not getting similar results, what gear setup are you using? In my current gear/spec, reforging my neck to Crit rather than Mastery results in a ~20 DPS loss, in the BiS setup it's closer to ~30 DPS loss. Maybe save your profile, click Export and paste the result in spoiler tags?

Thanks Slippykins I've never noticed the delay option...it was set to 0 and considering my latency ranges between 80ms and 120ms I've set it to 0,1 and the dps went down to what i'm actually pulling in a real environment.

(Setting owlkin frenzy to 0-1-2-3 talent points doesn't change the dps, i wonder if it is taken into account)

I'm still unsure about 2% damage 60% of the time (elicpse) or 170 haste because when haste does not reach a breakpoint it shortens the dot duration and without 4t12 this would cause me to refresh dots before leaving solar eclipse, wasting 2 gcd and losing NG uptime (and my mastery bonus would be lower with 5 t13 rather than 4 t12).
Considering the t13 bonus is a flat increase of our main nukes maybe increasing the bonus by 2% more every eclipse is worth more than 1/1000 faster tick rate on dots

Firstly, why are you turning off raid buffs? Any discussion about what's optimal will assume the presence of the major raid buffs, dummy DPS really doesn't matter beyond testing mechanics. However, you're correct, in that situation Crit is slightly better than Mastery according to the sheet.

I was turning off raid buffs because I was attempting to minimize external influences. Like I said, it was a simulation experiment. It's obviously not optimal (or realistic) for a Raiding situation, but I did find it curious, that with buffs turned off, crit is slightly better than mastery for me. As for dummy mode, even if I turn it off (FALSE) I get the same results with slightly more realistic dps. As I begin to fill BiS, and with Raid Buffs up, Mastery edges out Crit. Mostly, It was a curiosity, and I was hoping that there might be some explanation beyond "get better gear and get buffed" which was my own conclusion. I'm glad you found the same results that I did, as that means that I'm not entirely crazy! Thanks for looking at it. My personal conclusion, all told, is that Mastery ≈ Crit. and priority depends upon your Raid Comp. and gear.

(I reserve the right to change my mind at any time on any thing when presented with better evidence.)

EDIT: With an a few different raid comp's in mind, I've checked the Crit v. Mastery simulation again. With a melee-heavy composition (so, yes, Tecton, you are correct) Crit edges-Mastery, but with a caster heavy composition (preferred for DS, generally) Mastery edges out Crit. I intend to reforge into Mastery and see if I can squeeze a few hundred more DPS out of my gear.

I guess if you're raiding with an all melee 10 man raid giving you zero buffs at all, Crit edges Mastery out very, very slightly on paper. In any realistic gearing/buff situation, that's not the case. That doesn't mean Crit isn't inferior to Mastery in how you should evaluate your gear.

No, but 2856 haste should be enough to have cast times short enough to not refresh dots from an eclipse to the other (with Dark Intent). Considering that sooner or later I'll get the Heroic Insignia I thought that since the next haste breakpoint at 3600+ is unreachable the value of haste would drop when trinket proc + haste on gear makes the cast time of wrath reach the gcd.

Actually I have a very high uptime on Nature's grace and my Wraths are 1.4 sec.
When the trinket proc (normal version) the cast time reach 1.1sec.
Considering the fact that heroic insignia gives even more haste the cast time will probably reach the GCD.
If this happens every 140 seconds and the rest of the time my casts are pretty fast and takes me to the next eclipse 1-2 spells before dots drops off, then maybe mastery could be better considering that wrathcalc compute a Patchwerk fight and not a real fight.

If:
- Haste shortens the duration of my dots until I reach a breakpoint;
- The 2 tier pieces requires the presence of IS on the target;
- I have to move during the boss and cannot keep casting to move the eclipse bar
Then I prefer to have less haste (but enough to reach an eclipse in a reasonable time) to increase the duration of IS on the target and not have to refresh it (because if IS is not there, then the 2 pieces bonus is void) and balance the slower tick rate with bigger damages because of more mastery.

TLDR: in my opinion Mastery should change the weight of the tier bonus more than haste in a fight that involve movement and become better than haste when Haste > X value that let you reach the eclipse withing 1 sec before the dot ends. (only if you have DI)

(with 410 ilvl gear I will surely use the chest piece as offset because the stats increase is very big)

Perhaps you just enjoy math but you are talking about microscopic changes in DPS that are highly dependent on fight situations. You are way WAY over thinking tier itemization.

I've tested it on PTR the dps difference is abysmal... btw I have decided that even if wrathcalc says It's a DPS improve i won't use 5x t13 without 1x410 because the 4piece bonus is really really negligible.
While testing my dps on the target dummy I've noticed that with 5 sec less starsurge comes off the cooldown exactly when a Shooting Stars proc, making the bonus set half useless.
If i had a spell casting while the cooldown ended almost always a SS proc would nullify the bonus set or if the spell came off cooldown before a SS proc it was too close to the next eclipse making the cast of it out of eclipse a dps drop, nullifing once again the bonus set.

Technically, yes, Mastery would give you a higher damage output in P1 of the Blackhorn fight. However, I maintain a normal gemming/reforge profile for this fight so that I can contribute more strongly in P2. Getting Goriona to fly off sooner and killing Blackhorn himself more quickly is probably more useful than some more multidot damage in P1 (since P2 can be fairly rough on tanks/healers new to the fight). While you are working on P1, you might consider swapping in some Mastery trinkets until it starts getting smoother and replacing them once you guys are comfortably hitting P2.