Shadowpriest Compendium

[Sarawr]

It relies on very situational effects though; at certain fights it might be useful to have that but there hasn't been a moment I've seen the actual need for it though. Mind, my experience comes from raids that has far different mechanics when it comes to the encounters than it is with dungeons.

Here is where I've located the last two points:
http://eu.battle.net/wow/en/character/a ... nt/primary
Inner Sanctum - Also reduces spell damage taken by 4% when Inner Fire is active and increases movement speed bonus of Inner Will by 4%.

I have found placing talents on this one to be very useful; it adds to survivability and mobility, depending on if you have either IF or IW up. Again, it is situational. There is only one encounter where Inner Will is far more useful with the speed bonus; and this is Atramedes. Mechanics of that fight requires you to move a lot more than when it comes to the other encounters in the raid dungeons.

Although, if one goes for mana efficiency, then maxing out Mental Agility is advicable. Last point could then be placed on Phantasm for the 50% change of removing the movement impairing effects when using Fade.