For the Infernal Brimstone material, you should follow the “Infernal Brimstone” world quest on your map.

This way you will have some Blood of Sargeras and plus Blacksmith skill. And also, follow the questline in Legion blacksmithing. I suggest you get Mining as a secondary profession and farm mines in Legion map while doing your other stuff. Steelbound Devourer mount materials are mostly from Mining in Legion map. Steelbound Devourer Mount Mats, How to Get Steelbound Devourer? For the exact list of materials, you can check the image below. If you are still leveling, you need to know the Steelbound Harness mount recipe not drop from LFR. level to craft the mount and getting the recipe from Tichondrius in the Nighthold raid. Just follow the Blacksmithing questline all the way to max. So you will need to level up your Legion Blacksmithing to craft this mount. Steelbound Harness is taking place in Legion content. Steelbound Harness Guide and Steelbound Devourer Pattern

I suggest you try it once if you have Blacksmithing profession for easy wow gold farming. It goes around 45k gold on Auction House and it’s not so hard to make it. Some people calling it Steelbound Devourer but both are the same, so you are in right place too if you looking for Steelbound Devourer or Steelbound Harness doesn’t matter actually. Steelbound Harness mount is a crafting mount by Blacksmiths in wow.

Mounting made easy legion quest