Oh, if in 5-man instances that are non-heroic, it's ok if ure not the top dps. In short fights, our dps won't look impressive because it takes time for our debuffs on mobs to scale (shadow weaving, misery) not to mention our DoTs can't reach its full dmg potential when the mobs dies within 5 seconds. Also, our burst dmg is sh!t compared to other classes.

U should be the top dps, if not the 2nd in heroics tho, esp during boss fights in heroics. We hardly have to CC. All we do is pewpew!

As for your spell rotation, the only change I would make is to remove VE from your rotation. Leave the healing to the healers, and concentrate on your pewpew. U save up to 1.5 sec not using VE. Also, when u say u are monitoring ur DoTs using NECB, are u re-casting VT when there is 2 - 1.5 secs left on the bar or right after it's ended?

For boss fights, you can start your spell rotation with a rank 1 SWP for the misery debuff and 1 point into the shadow weaving debuff. Ur next spell immediately does 7% more dmg, at a cost of 25 mana.

Also, u might want to get Quartz, or learn to time casting ur spells 0.25 secs sooner, since when playing with our lag, our spells are over sooner than we think.

Around 20 is the norm for maybe a 3 hour duration. But I usually end up using about 14 and even less.

Us undeads use less mana pots cos we dish out more dmg than other shadow priest races with our Inner Focus + Devouring Plague (except for trolls in certain situations ie. berserking during curator), thus returning more mana with VT on.

The best time to consume ur mana pot is when ure past the 3k mana mark, so that u will have a fast 2 min cd on pots, or wait till ure past 4k and use shadowfiend. With a 5 min cd, if you use it early on a long encounter, the shadowfiend will be up again during the last quarter of the fight.

Knowing when to use ur shadowfiend can save u a few mana pots. Like just b4 Gruul does his shatter. Happened to me lots of time.

Back to the question, yeah if its one of those wipe nights, expect to use more than 20. I console myself by telling myself I wear cloth. :`(

Another thing, u should be able to gauge how well or how badly the raid is going. If its going to be a wipe, then save urself on the mana pot and use shadowfiend instead. Those long ass runs back to the instance and having to rebuff will guarantee that ur shadowfiend cd will be free by then.

Hope this brings u a little bit of comfort in ur wipefest tonite.