Someone did a shadow rework for leveling. It's the Shadow.cs replacement for Singular. All it does is start with MB, then two MF, then SWD. That's all it takes for the most part to kill something. I'm currently level 48 and I have the SWD glyph which gives you back something like 3% of your mana over 3 seconds. It's working pretty well right now, but the quests in Searing Gorge / Burning Steppes are kind of tweaky, so it's slower than usual, but I can tell that shadow is a lot better now that I'm using that shadow rework. Just look in the priest section. I can't remember the name, so you'll have to read into each of them to find it.