You can level as either. I have even managed to take Single mastery Occultist and Necromancer from 1-100.
You can see the GT links for every 10 levels near the end of the Beginner builds section in this guide: The Carnival - A Guide to Pets
I have a question.
Did you try to use Stormbringer of Malmouth for this build? or any others?
Now I am wondering to transfer my Cabalist to one of your builds.
I haven’t really played with this one since Cataclysm offhand nerf nor have the char save file atm, so can’t really test it, but last time I used Stormbringer, I had mana issues IIRC. Worth testing it out though if you want to go for it.
So this is literally perfect for me. I’ve been meaning to try out some pet builds for awhile, and I just stripped/prepped my cabalist for a respec. Furthermore, transmuted blightfiend is a particular pet concept that has tickled my mind since I first read it. So when I said “literally” I was literally using literally literally.