Let me start by saying that my main spec is Holy, with Shadow being an offspec intended for soloing purposes and such. In dungeons and raids, I usually end up in the healer role, something that I've been doing for years. Also, for years, I've been playing with the same group of reallife friends, group being composed of a Warrior (Fury/Protection), Death Knight (Blood/Unholy), Mage (Arcane/Fire), Druid (Boomkin/Resto) and me (Holy/Shadow). We're all at 350-355 iLevel, so for instance CC-ing in HC's is an option, not a requirement anymore. My gear is strictly Healing gear, it's not specifically attuned (gemmed or enchanted) towards Shadow.
Yesterday we entered Halls of Origination for our random daily and the War and DK decided between them who would tank this run and who would DPS, like they always do. The Druid then said that she could choose her role as well, in agreement with me. For a change (I insisted it was for her healing practice ), we decided that she would go healing on this one and I would DPS as Shadow.
On single targets, I was pulling somewhere between 10-14k DPS, depending a bit on boss mechanics and time warp availability (SW:P, VT, DP, MF till orbs at 3, then MB - possibly augmented by Dark Archangel, refresh VT and DP as needed). But on multiple targets, I was struggling somewhat. I know Mind Sear isn't the greatest spell, so I was multi-dot'ing. However, with 4 mobs up, multi-dot'ing is somewhat hard, to keep all the dots running on all mobs (SW:P + VT on all, and a DP on one of them). At a GCD (plus reaction speed and target switching), by the time I had applied the last dot, the first one would be about to drop off, too late for Mind Flay to refresh SW:P and besides, VT would need a refresher as well. And to make matters worse, tab-targeting works awkward at best, as it doesn't cycle through a list but just randomly seems to target other mobs in the vicinity, making it harder yet to apply Mind Flay to targets from which the SW:P was about to drop. On top of that, I also tried to mingle Mind Blasts into it, as well as proc'ing my Dark Archangel at opportune moments.
Sooo, I guess I am doing something not quite the way I should be doing - especially since one of my friends mentioned how Shadow priests were currently being at the top of the damage tables. As such, anyone who can give me hints and tips on multi-mob fights? Things I should be doing and things I should most definately not be doing, based on what I did yesterday?