Shadowpriest stat priorities
In the old days, out DoTs could not crit, Haste only reduced our Global Cooldown and thus Spelldamage reigned supreme. Many things changed, and all spellcasting classes have become much more egalitarian. Our DoTs benefit normally from Haste and Crit, issues with recasting DoTs when you get a spellpower buff have been fixed and even our Mastery now is useful.
1) Spell Hit (Until Hit Cap)
In a raiding situation, your DPS does not matter if you cannot reliably hit your target. Because of this, we need the Spell Hit stat, which reduces the chance for bosses to resist our spells. You need 15% Hit to have no spells be missed on a boss (= Hit Capped). Experienced Shadowpriests should be able to go with 13% Hit and not worry about it.
Shadowpriests gain an amount of Hit rating equal to their Spirit. Draenei priests have a 1% bonus to Spell Hit due to their Heroic Presence. Expertise on items also gives Hit, but usually these items are more Hunter- or Melee-related. Humans, Dwarves and Trolls get a 1% Expertise bonus on some weapons (maces, swords, wands) and this bonus translates into a Hit bonus for spells. So these races only need 12-14% Hit on gear to be comfortably hitting their raid targets.
Your Shadowfiend or Mindbender has the same Hit bonus as you do, meaning that if you are hitcapped, your pet will not miss either.
Damage is king, and despite everything else, Spellpower is still a very efficient way to increase your overall damage. Spellpower does not affect all your spells equally however; some spells only add part of your Spellpower to their damage (or damage per tick), which we refer to as the Spell Coefficient. Since patch 4.0.1, Spellpower has been removed from most items, and you gain Spellpower directly from your Intellect rating.
Intellect in Mists of Pandaria will no longer give Mana, meaning its use is lessened and needs to be evaluated compared to secondary stats when going for enchants or gems. With gems usually having double the secondary stat as before, Int/Haste and Int/Hit or Int/Spi gems become a little more useful.
Haste and Crit are values that you want to have a certain balance to. It may seem a bit mystical, but I’d say that having a 2:1 ratio would be ideal. Haste makes us cast our spells faster, so we go out of mana faster. It also allows us more “checks for whether we crit or not” per time frame.
As an aside, Haste does not work like most people think; it does not reduce the cast time by X%, it simply dictates the speed at which spells are being cast. So 100% haste will reduce the casting time by half. Imagine this:
- We cast 1-second spells, 25% crit chance, 0 haste, 1000 damage on a normal hit.
- In 12 seconds we cast 12 spells, 3 of which crit for 2000, 9 deal 1000 damage.
- Total damage done = 15k over 12 seconds (1250 DPS)
- We cast 1 second spells, 25% crit chance, 100% haste, 1000 damage on a normal hit.
- In 12 seconds we cast 24 spells, 6 of which crit for 2000, 18 deal 1000 damage.
- Total damage done = 30k over 12 seconds (2500 DPS)
As you can see, the benefits of Crit are obvious. However, Haste allows you more crit chances over the same period of time, as well as more spells cast (and thus damage done) in that same time frame. This is why Haste increases your DPS more than straight Crit does. A balance between Haste and Crit of about 1:2 will ensure a comfortable damage curve with enough crits for your Shadowfiend cooldown.
Haste is currently one of our best stats, and you should seek it out over Crit and Mastery. Haste and Mastery also have a positive relationship, meaning that having more of the one will make the other more valuable.
Crit and Mastery have about equal values at the moment. Mastery and Crit both simply deal double damage effectively. As they are cumulative (a double hit and a crit) this means that even though Crit benefits the cooldown on Shadowfiend, you still want to balance them out. This allows you maximum damage without hitting the diminishin returns too hard.
Edit 18/1/2013: From my own experiences this expansion, I have to conclude that while Haste is top priority, Crit and Mastery change the way we deal our damage. Crit will increase the value of all our spells, but by a margin less than Mastery does – this makes Crit a superb stat for single-target fights. It also synergizes well this way with Mindbender, allowing us to use it frequently. As for Mastery, it will increase our DoTs – but also Mind Flay and Mind Sear. This makes this stat the go-to for heavy AoE fights and multi-dotting fights.