Originally Posted by
SkillOverKill
Raid composition counts for a ton, trying to get all your castery buffs is critical - if you are going to reroll for your raid, reroll sometihng that synergizes imo. Also, Boomkins aren't bad right now - unless there is a serious reason for the swapping to shadow I'm not following - you might consider going back to Boomy?
8% spell damage debuff, 10% spellpower buff, 5% spell crit debuff (scorch, shadow bolt), and Dark Intent all have an Enormous impact on shadow's dps - trying to get everyone in your raid as many buffs as possible is essential.
For most fights, the simplest thing to getting more damage out of a spriest or boomkin for that matter - is MOAR DOTS - and targetting a tank just before an aoe phase begins to pre-sear the spawn spot, potentially with a pre-fade before it so you don't instantly pull aggro off the tank. Keeping up Empowered Shadows for either of the above is key, empowered shadows can be 30-50% additional dot / channeled damage depending on your mastery - that's an Insane amount (with 4pc, it's less of a worry).
Shadow and Boomkins both shine in multi-target scenarios and aoe phases - but for single target many people have covered or cited good resources already.