This Legion Alchemy leveling guide will show you the fastest way how to level your Legion Alchemy skill up from 1 to 100 as inexpensively as possible.
Alchemy is the best combined with Herbalism. You can save a lot of gold if you level these two professions together because you can farm all the needed herbs.
If you are still leveling your character, I recommend trying Zygor's 1-60 Leveling Guide to help you get to max level faster. And if you are low on gold, you can also try his Gold Making Guide.
Learning Legion Alchemy
First, visit your Alchemy trainer Deucus Valdera at Dalaran. Just walk up to a guard in the city, you can ask them where the Alchemy trainer is located.
After you learned Alchemy, pick up the quest
Get Your Mix On (requires level 10) from Deucus Valdera.
The recipes for the potions and the Crystal Vials are sold by Patricia Egan. She is in the same room where the trainer is.
You will need 9 
[Yseralline Seed] to make the potions for the quest.
After you completed the quest, you will learn 
[Legion Alchemist]
Leveling Alchemy
Goblin characters have +15 Alchemy skill because of their passive 
[Better Living Through Chemistry]. An extra 15 Alchemy skill means recipes stay orange for 15 more points. You can save a lot of gold by doing lower level recipes for 15 more points.
Farming guides: 
Dreamleaf farming, 
Aethril farming, 
Foxflower farming, 
Fjarnskaggl farming, 
Starlight Rose farming
4 - 9
5 x 
[Rank 1 - Ancient Mana Potion] - 20 Yseralline Seed
Keep these, you will use them for the next recipe.
9 - 15
6 x 
[Rank 2 - Ancient Healing Potion] - 24 Yseralline Seed
Don't forget to buy the rank 2 healing potion recipe from Patricia Egan! You can discover the rank 3 potion recipe from making these.
Keep these, you will use them later.
15 - 20
5 x 
[Rank 1 - Ancient Rejuvenation Potion] - 5 x Ancient Healing Potion, 5 x Ancient Mana Potion
20 - 50
35 x [Rank 2 - Ancient Healing Potion] - 140 Yseralline Seed
This recipe will be yellow for the last 10 points, so you might have to make more.
If you discovered the rank 3 recipe, you can make this one up to 70.
Unlock more Alchemy recipes
Alchemy recipes are unlocked by doing quests given by Deucus Valdera at Dalaran.
You will need level 45 to unlock the recipes used below. The quests are pretty straightforward, so I will not write down the details of every quest. You will unlock the flask recipes sold by Patricia Egan after you finish Testing the Calibration quest. (around the 26th quest in the quest chain)
You should finish every Alchemy quest given by your profession trainer, that's the only way to get the first rank of every recipe. Almost every recipe will be sold by Patricia Egan after you complete the quests.
50 - 70
Make 25 from any of these:
You will need 10 from each for the Testing the Calibration quest.
- 25 x
[Rank 2 - Leytorrent Potion] - 25 x Starlight Rose, 50 x Aethril, 50 x Dreamleaf - 25 x
[Rank 2 - Potion of Deadly Grace] - 25 x Starlight Rose, 50 x Fjarnskaggl, 50 x Dreamleaf - 25 x
[Rank 2 - Potion of the Old War] - 25 x Starlight Rose, 50 x Foxflower, 50 x Fjarnskaggl - 25 x
[Rank 2 - Unbending Potion] - 25 x Starlight Rose, 50 x Aethril, 50 x Foxflower
These will be yellow for the last few points, so you might need to make more. If you discover any of the rank 3 recipes while making the potions, you can craft the rank 3 recipe up to 90.
Rank 2 recipe locations:
[Rank 2 - Recipe: Leytorrent Potion] - Dropped by Wrath of Azshara in Eye of Azshara dungeon.- [Rank 2 - Recipe: Potion of Deadly Grace] - Droppey by Advisor Melandrus in Court of Stars dungeon.
- [Rank 2 - Recipe: Potion of the Old War] - Dropped by Advisor Vandros in Arcway dungeon.
- [Rank 2 - Recipe: Unbending Potion] - Dropped by Dargrul in Neltharion's Lair dungeon.
Alternative recipe:
If you have a bunch of 
[Blood of Sargeras], then you can also make 
[Potion of Prolonged Power]. The rank 1 recipe is a world drop, but the drop chance is very high. You will get one while doing World Quests and killing stuff.
If you are Revered with the Nightfallen, then you can get the rank 2 from First Arcanist Thalyssra at Suramar, and then you can make this one up to 90.
You should also check if Na'zak the Fiend is the current World Boss, because he drops 
[Rank 3 - Recipe: Potion of Prolonged Power]. Then you can level with the Rank 3 potion recipe to 100.
70 - 100
While crafting the rank 2 flasks, you can discover the rank 3 version of that flask. The rank 3 flask is orange all the way up to 100, so if you are lucky enough, you will have to craft a lot fewer flasks. Discovering a rank 3 flask recipe is entirely based on luck, you might get it after 10, or you might need to craft hundreds.
It's pretty easy to miss when you discover a rank 3 recipe because it just simply appears in your inventory as a recipe. Try to queue up only 5 Flask at a time and keep checking your bag/chat for the recipe.
Choose only one:
- 60 x
[Rank 2 - Flask of Ten Thousand Scars] - 420 Starlight Rose, 600 Aethril, 600 Dreamleaf - 60 x
[Rank 2 - Flask of the Countless Armies] - 420 Starlight Rose, 600 Aethril, 600 Foxflower - 60 x
[Rank 2 - Flask of the Whispered Pact] - 420 Starlight Rose, 600 Fjarnskaggl, 600 Dreamleaf - 60 x
[Rank 2 - Flask of the Seventh Demon] - 420 Starlight Rose, 600 Fjarnskaggl, 600 Foxflower
These rank 2 flask recipes will be green for the last 10 points, so you might have to make more or fewer. It will greatly depend on your luck.
Rank 2 Recipe locations
You got 3 of these already if you completed the Alchemy quests.
- [Rank 2 - Recipe: Flask of the Whispered Pact] - Dropped by the last boss in Mythic or Heroic Blackrook Hold.
- [Rank 2 - Recipe: Flask of the Countless Armies] - Dropped by Helya in Mythic or Heroic Maw of Souls.
- [Rank 2 - Recipe: Flask of Ten Thousand Scars] - Dropped by Odyn in Mythic or Heroic Halls of Valor
- [Rank 2 - Recipe: Flask of the Seventh Demon] - Dropped by Cordana Felsong in Mythic or Heroic Vault of the Wardens.
I hope you liked this Legion Alchemy leveling guide, congratulations on reaching 100!