How do I add an essence like Breath of Dying to my task bar? Been gone awhile and I’m fuzzy on some things. 
The essences appear in the General tab of you spell book. You can drag it onto your bar from there.
Edit: I believe you can drag them from your heart of azeroth window as well if they are equipped.
I found concentrated flame but not the others and I couldn’t drag any either. Wonder what I’m missing.
You only get a major power from the essence in the middle. The middle essence is the only one that can be put on the action bar. If you want to change essences you have to place a new on in the middle slot of your necklace.
Ahhhhh… thanks. And rats!