At Level 78, you unlock the stat Mastery, which increases your Shadow damage. When you unlock this stat you should switch your level 56 talent from All Will Serve to Clawing Shadows, as it benefits more from the Mastery. The mechanical change when using Clawing Shadows is that you will be able to pop Festering Wounds from a distance. If you want to attack multiple targets with Clawing Shadows using Death and Decay's cleave effect, make sure you play the Death and Decay below your own feet instead of the target.
As you're leveling, I generally recommend you just follow the natural flow of the progression through each zone. They're laid out fairly reasonably. But don't be afraid to hop around, especially if you're near a quest objective. You shouldn't actually need ALL of the zones listed to reach 62. Pick the ones you like best. It's much more important to simply be as focused as possible and flow from one quest to the next.
Zygor's Leveling and Loremaster guide is the ultimate tool for players who want to level up quickly and earn the coveted Loremaster achievement. This guide will lead you quest by quest through every zone, telling you exactly where you need to go, how to complete objectives, and everything else required to reach level 120 in the fastest time possible.
The Horde 12-25 (Barrens + Stonetalon Mountains) guide has been rewritten and revamped. In addition, there has been numerous tweaks to the speedrun route to make things faster and easier to follow. Also, in case you haven't noticed I am now adding about 40% more info per step and redoing all the images. Unlike with my previous vanilla guides, I am now giving a brief explanation of where to go and what to do with each step along with any other helpful tips.
But when it comes time to level another character for any reason, this pace is going to make me think twice. And that's a shame. I'm not someone who gets any particular joy out of instant-boosting a character to max level. There are dozens of zones -- no exaggeration -- that I wouldn't mind experiencing again, if I could do a few of them at a time and feel like I was making meaningful progress on another level-110 in the process.
Fourth, beginning in Mists of Pandaria with the Halfhill farm, and continuing in Warlords of Draenor with various garrison buildings that produced resources, Blizzard has been making trade goods more plentiful and easier to obtain. In Legion, herbs, fish and enchanting materials were so abundant that a very small population of gatherers could supply more raw materials than the economy could consume.
The additional recipe ranks can be obtained either by exploring the outdoor Broken Isles zones or as rewards when you dive into the dungeons of the region. If you’re feeling up to the challenge, you can aim to hit skill level 100 and player level 100 to open up profession world quests, which rewards higher rank recipes for your Legion gold making operation.
These two expansions are virtually identical in terms of exp/h. I personally favor Mount Hyjal, and think it's very slightly faster. But if you know Jade Forest well you can just as easily keep up there. Ultimately you'll end up doing both anyway, so it's mostly academic. Every time I've tested Valley of Four Winds or Deepholme, or any other zone in MOP/CATA's level range, they were worse exp/h. You should not even need to complete both zones to ding 91, so it's more important to just pick one and go.