**Most of this information comes from http://www.icy-veins.com. If anyone has a "better" guide, please feel free to share.
Stat Priority
1. Intellect
2. Hit, Spirit, or Expertise (until 15%)
3. Haste (until soft cap [8085 for non-goblins, 7584 for goblins])
4. Critical Strike
5. Mastery
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Talents
Tier 1
Pick your favorite, as they're all CC abilities and won't affect dps.
Tier 2
Angel Feathers has the most versatility and isn't limited by a long cooldown (or restricted by Weakened Soul.) That being said, Body and Soul is viable. The only one you should probably avoid (outside of extreme gimmick fights) is Phantasm (as it's more of a PvP talent.)
Tier 3
From Darkness, Comes Light and Mindbender seem to be the top picks here, with most of the discussions I've seen leaning toward the former. Shadow Word: Insanity is an option, but it causes you to have to time eating your Shadow Word: Pain to just before it falls off. To me, it just seems like a lot more upkeep. Mindbender (much like Shadowfiend) should be cast on cooldown (except when saving for burn phases, like with Hagara or Madness) so likely won't cause you any more headaches than Shadowfiend normally does (though it has a shorter cooldown.) From Darkness, Comes Light allows you up to 2 stacks of a free, instant Mind Spike that won't eat your DoTs. It combos great with Glyph of Mind Spike, giving you an instant cast (or sped up, with one stack) Mind Blast.
Tier 4
Desperate Prayer and Angelic Bulwark are the top two choices here. Both are pretty good for survivability. Desperate Prayer gives you a 30% heal on a 2 minute (?) cooldown, which lets you time it for when you need it most. Angelic Bulwark is a passive ability that auto-procs a bubble if you get below 30% hp (with a 90 sec internal cooldown.) Spectral Guise is a pseudo-vanish (it doesn't remove you from combat) for priests and seems to be geared more towards PvP.
Tier 5
There are still some discussions as to which is "best" for dps, but I don't think you'd go wrong with any of them in this tier. Twisted Fate gives you increased damage after you've hit/healed something that is below 20% hp. In boss fights with adds, I could easily see procing this off the killing of adds to get the damage boost, or combo it with Glyph of Dark Binding to get the healing proc off of raid members. Power Infusion is the same thing Disc Priests were providing before and makes for a nice, controllable dps boost. However, everything I've read suggests to avoid using it during Heroism/Bloodlust. Divine Insight has a chance to proc off of Shadow Word: Pain (so really shines in multi-dot scenarios) to reset the cooldown of Mind Blast and make it instant/mana free. This will allow you to build up Devouring Plague more often (which is a pretty high damage spell.)
I personally like Divine Insight, but again, I don't think you'd be wrong in selecting any of them at this point.
Tier 6
These three talents all have their uses and should ideally be selected based on the type of encounter. If everyone is stacking/lining up (raid members and/or enemies), Divine Star can put out some pretty good numbers. In a spread out scenario, you might be better off with Cascade or Halo since Cascade attempts to target those farther away and Halo increases damage/healing up to the 25 yard mark.
Personally, I love Halo (largely in part due to the graphic) but will probably keep a stack of Tomes on me to be able to switch out for various boss fights. Also, for those who have problems with Halo positioning, you might try this add-on.
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Glyphs
Major
Glyph of Mind Spike - Required. Great synergy with From Darkness, Comes Light.
Glyph of Dark Binding - Recommended. Great boost to utility and survivability.
Glyph of Fade - Optional. Small boost to survivability.
Glyph of Dispersion - Optional. Shorter cd on Dispersion allows more usage for survivability/mana returns.
Glyph of Inner Sanctum - Optional. Provides an all around utility boost.
Glyph of Levitate - Optional. Good for high movement fights.
Glyph of Mind Flay - Optional. Small boost to mobility.
Glyph of Reflective Shield - Optional. Minor boost to dps when you take damage (works great for soloing.)
Minor
Pick whichever you like, as these are all cosmetic in nature.
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Rotation
Single Target
1. Devouring Plague (3 Orbs)
2. Mind Blast
3. Shadow Word: Pain and Vampiric Touch
4. Shadow Word: Death
5. Mind Flay
2-4 adds that take 15+ seconds to kill
Keep Vampiric Touch/Shadow Word: Pain on as many targets as possible. Enjoy Mind Spike/Mind Blast procs (with appropriate talents.) Devouring Plague when possible. Use Mind Sear instead of Mind Flay.
Adds that die quickly
Mind Blast/Mind Spike
5+ adds
Mind Sear (ideally targeting the tank or melee dps that is in the middle of them all.)
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Gems
Meta
Burning Primal Diamond
Red - Primoridal Ruby/Perfect Pandarian Garnet
If you're having trouble getting hit cap use Precise, otherwise Brilliant.
Yellow - Vermilion Onyx/Perfect Tiger Opal
If the socket bonus is anything except +60 int use Brilliant, otherwise use Reckless. It would seem Quick Sun's Radiance/Perfect Sunstone may also be viable in belt buckles.
Blue - Wild Jade/Perfect Forceful Alexandrite, Imperial Amethyst/Perfect Veiled Roguestone
If you're having trouble getting hit cap use Sparkling/Rigid, otherwise use Purified/Energized.*
*Gear levels will effect these. Icy-veins suggests Purified, whereas AskMrRobot is showing me that Energized is better for my set up.
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Enchants
Head
These don't exist anymore, quit looking for them.
Shoulder
Greater Crane Wing Inscription
Secret Crane Wing Inscription (scribes only)
Cloak
Superior Intellect
Lightweave Embroidery (tailors only)
Chest
Glorious Stats
Mighty Spirit (if still struggling to reach hit cap)
Bracers
Super Intellect
Fur Lining - Intellect (leatherworkers only)
Socket Bracer** (blacksmiths only)
Gloves
Greater Haste
Socket Gloves** (blacksmiths only)
Synapse Springs** (engineers only)
Belt
Living Steel Belt Buckle
Legs
Greater Cerulean Spellthread
Greater Pearlescent Spellthread
Master's Spellthread (tailoring only)
Sanctified Spellthread (tailoring only)
Boots
Pandaren's Step
Greater Haste
Rings
Greater Intellect (enchanter only)
**Stacks with normal enchant
I'll finish this later.
