Why this build
How the build works
This Shadow Priest build trades control for sustain and steady damage. Spirit Tap doubles your Spirit for 15 seconds after a kill and lets 50% of your mana regeneration continue while casting. Chain your kills and you rarely need to drink.
Damage comes from three places. Improved Mind Blast takes 2 seconds off Mind Blast’s cooldown, so it comes back more often. Mind Flay is your channel filler, and Improved Mind Flay makes each tick deal 20% more than the one before, so a full channel is worth far more than a clipped one. Improved Shadow Word: Pain adds 6 seconds to the DoT, which often covers a whole fight.
Shadow Weaving gives every Shadow spell a stacking 2% damage increase on the target, up to 10% at 5 stacks. Shadow Focus adds 3% Shadow hit so fewer spells miss. Vampiric Embrace, the last point, heals your party for 20% of your Shadow damage and is the prerequisite for Shadowform later.
Leveling tips
Spirit Tap goes first: from level 10 it is the biggest saving in downtime. Improved Mind Blast and Improved Shadow Word: Pain speed up early kills. Mind Flay arrives at 20 with the 50% slow, which helps against melee mobs.
Open with Mind Blast, apply Shadow Word: Pain, fill with Mind Flay, and finish with your wand. In dungeons, use Vampiric Embrace on the main target. Shadowform needs 30 points, so you will not see it during the level-30 beta.
Changes in WoW Forever
Improved Mind Flay, Dark Inspiration, Devouring Contagion and Early Demise are new. Shadow Weaving now only boosts your own Shadow damage. Devouring Plague and Shadow Word: Death are baseline spells for every priest. Silence no longer requires Improved Psychic Scream. On 30 Oct, Shadow Word: Death backlash at rank 4 rose to 30% of your maximum health, so use it with care outside execute range. Talent text here includes the Priest hotfixes of 30 Oct.
Toward level 60
The planned endgame build is close to 14/0/37: Darkness, Silence, Devouring Contagion, Early Demise and Shadowform, with Twin Disciplines, Mental Strength and Meditation from Discipline. Guides disagree on a few points, so treat it as provisional.