Thanks for that analysis, napsilan. I've been playing with the two trinkets for the last week and have finally settled on FoM full time. Even though, as you note, it is possible to get higher regen through Mandala--especially in a long fight with two shadowfiends--it's a non-trivial inconvenience to do so. Especially as an engineer, I find it much easier (if less beneficial) to line my shadowfiend up with gloves, and with mandala I often found myself waffling between delaying shadowfiends to get better proc alignment, and impatiently just using shadowfiend asap. Hymn of Hope is even harder to align with Mandala proc as its timing is largely dictated by a lull in healing needed for the fight, especially on 10man.

The other major issue is that the proc'd int is just not as useful for healing as consistent int. There is simply no way to guarantee that the mandala procs will coincide with the times healing is really needed, making its throughput value questionable. The spirit proc, on the hand, is only going to be wasted if you're already at full mana--in which case you probably don't need a trinket bonus at all.

The last point, if pretty minor, is that FoM should have a slightly higher uptime than Mandala: FoM has a longer duration (and correspondingly longer ICD), but the same proc chance, i.e. same average time to proc, meaning lower relative downtime.

It's been a while since I've played Spriest but one would assume mind sear under Dark Evangelism would be the best method (assuming the 90second cooldown allows it's use on each cycle). In theory they shouldn't survive long enough to justify putting SW:P on each one.

Depending on how far into the fight you are (e.g. how many 'slimes' are up) and how well they are clumped, either Mind Sear or Vampiric Touch.

As noted above, they don't live long enough to justify SW:P, and VT is your hardest-hitting DoT.

I'll echo what's been said above for using DoTs on the slimes, specifically VT. At the current time Mind Sear hits like a wet noodle, so it's often not worth the cast and high mana cost to worry about it. If Just VT isn't working well enough, throwing up SWP wouldn't be a terrible idea, especially because you're likely to start PROCing orbs like no tomorrow.

Alternatively, if you're not too worried about your orb generation, use Mind Spike and tab through considering that the spell does a decent amount of burst damage with a relatively short cast time. The only big issue with this approach is that MSpike will eat your orbs, which could leave you without Empowered Shadows.

Shadowpriest question:

I know that the haste of a DoT is determined at the cast time (i.e. haste buffs will not change the speed of DoT ticks if they occur after the DoT is already cast). Do damage buffs work the same way? That is, if a trinket procs 1920 spellpower after the DoT has already been cast, will the DoT benefit from that proc or would I need to refresh it?

Yes, damage buffs work the same way. Yes, you would have to recast it. No, you probably shouldn't.

The generalized answer to "should I refresh my dots early to account for [...]" is "no". It's generally not worth the lost casting time to do so. There are plenty of exceptions, but if you aren't sure, just refresh as normal.

I have a newbish question about gear and stats: is it better for a spriest to use spirit for hit, or better to just go for straight hit? A few people have told me to "just use healing gear" because I get the hit that way, but (and my logic might be off here) if I got a few pieces with a dedicated hit stat, wouldn't that free up my other slots for pieces without spirit (and hence other juicier stats like mastery/crit/haste)? On the other hand, I could see how spirit would be fine, since most pieces have equivalent spirit and hit amounts (eg +168 of either hit or spirit...).

Human priests definitely prefer spirit, though, all else equal (3% bonus). Even that is minor enough that it usually only matters if items are carbon copies except one has hit and one has spirit.

When should we Mind Sear over using multi-dotting? I am thinking of specifically of a fight like heroic Maloriak, where the adds have a lot of health. What is optimal for dps on the Dark Phase? So far, I have been putting VT/Pain on all the slimes and making sure to keep up ES/Evangelism, but I am wondering if Mind Sear spam with ES/Evangelism would yield higher dps?

I have seen random forum posts about people saying 5 mobs, 7 mobs, never, etc. and was just hoping to help clear this up. Thanks!

I am trying to figure out what gear I should be going for right now in non-heroic raids. I have looked at priests from some top guilds and noticed that most of them just go for all out haste gear. I use SimulationCraft for my shadow set and it gives me stat weights which I can then use to find my current BiS gear. However, it doesn't work for Holy and in the holy priest compendium, I don't really get the stat box they give and if I should be using that somehow.

Is there a way to know what sort of stat weights I should be using so I can figure out some BiS gear for holy or should I just focus on getting spirit gear with haste and mastery?

is the amount of Lightwell ticks affected by haste - and if so - by the caster's haste or users haste? (because pre-potting/trinketing haste for a pre-fight Lightwell could be interesting then).