
You will start your profession from skill 1 again and you don't get back the rank 2-3 recipes that you got from vendors/wolrd quests. Basically, you will only get back the Legion questing recipes, no old world recipes or anything. If you got a recipe from a mob and not a quest, you have to go and farm that recipe again. You will only get back the recipes you got from questing. Books cost 1000g and you can simply buy them from a vendor near your trainer at Dalaran. And there's no way to redo a quest if you drop and relearn a profession, so books are a solution to giving you back the rewards from completed profession quests. In Legion, most recipes are from quests. Gathering professions will also have ranks, with each rank you can usually get more material from a mob/node or have a chance to get Blood of Sargeras. Higher rank recipes allow you to craft an item for fewer materials, or you get more potions/food for the same amount of material. Filter options for slots, category, and sources. The new profession window is much larger. There is a new Unlearned tab where you can check which recipes you are missing and where to get them. level quests, you can start doing them as you level up, but there are level requirements for later quests so you can't finish them all at level 100. You learn most recipes from quests, but there are still a few recipes that drops from creatures. (like smelting different kind of metals, and ores for blacksmithing) Each profession will get a unique quest line, these quests will immerse your character in the story and they will try to mimic what you would do if you had that profession in real-life. This guide provides an overview of the new items and professions changes in Legion.
In general, honestly, I think it’s kinda dumb that we can’t learn and maintain all professions on a single toon.Professions in World of Warcraft Legion will be drastically different than how they worked in Warlords of Draenor with garrisons. But yeah… fair warning before you do it: treat it as if you will start over if you want to switch back, because that is 99% what you will basically end up doing. I was pretty confused and angry but mostly at myself for switching in the first place, and also not doing proper research before switching. Turned out I recovered almost nothing of what I previously earned. But what I thought I understood about it was wrong. I eventually wisened up and went to go switch back to alch/herbs, thinking alch shouldn’t be too much of a hassle to get back up to speed, based on what I thought I understood about recovering previously learned professions.
When BfA released I dropped it and Herbalism for Leatherworking / Skinning because I foolishly thought crafted armor professions would actually be useful this expansion. I was an alchemist on my DH during Legion and spent a lot of time leveling it up, farming recipes, etc.