There are 19 reagents that you must harvest 10 times each (Looting or buying dose not count) Reagents are also on a 2 day respawn (Except for Seaflax which is 3 days) You do not need to harvest Essence of Fate, it's the only reagent that you do not
need to collect for the achievement.
If you are farming a certain reagent remember that you can sleep in a bed to pass the time and make it spawn again.
Also you do not need to have 10 of everything in your inventory at once, you can sell/use anything you harvest and it will still count.
If you leave this achievement until one of the last achievements that you go for, it will be very simple. By then you will most probably only be missing one or two reagents of the 19, Which are the rarer ones like White Flake,Scarab Salts or Seaflax.
I suggest first doing the ones in Seawatch like the Seaflax. If you do that and don't get the achievement then start to do the White Flake and what ever else you think you might not have.How to get the Castle (Seawatch)
To start this quest travel to Klurikon - SeaWatch, Note that you will be unable to travel here until you have completed the quest "Breaking The Siege"
Once inside speak with Byrn Elgar. He will inform you that the previous tenants have left the castle over time, he also mentions that you're the only one deserving of the Castle it's self. But he may be a little crazy... After talking to him you will begin the quest "Ghost of Seawatch"
Now on to getting back the rest of the staff, starting with Conni.Part One:Find Conni:
Locate the Fae woman "Conni", she is inside the prison of Castle Ansilla, Western section. However one dose not simply enter Castle Ansilla. You will need to run around the side of the Castle to locate a drain pipe to get inside.
When inside you should receive a quest from "General Fynn" But it is not required to free Conni.Find the Dungeon Key:
Upon talking to Conni, she'll tell you to locate a key to the prison gate in the Eastern part of the castle.Open the Dungeon Door & Talk to Conni:
Return to Conni with the key to free her, Conni will be available to train you in Master Alchemy (7-9) inside Seawatch now. Then return to Byrn Elgar, when you return to Byrn he will start the second part of the quest.Part Two:Find Erion Odi:
To find Erion Odi your second retainer (Healer), go back to the North section of the Caeled Coast(Klurikon) to Odi's Camp. The Sergeant is more then willing to leave but wants a replacement first. Seek out Private Cornall to the southwest and convince him to replace the Sergeant. Return to Odi who heads off to Seawatch.Part Three:
Once that's handled, go for the last servant, a merchant named "Astor Colliani" he will be ransacking corpses for money in Mel Senshir. Talk to the gnome merchant and take the dagger (a war trophy) he wants from the soldier in the tavern her name is Fridi Edstar. You can attempt to buy or persuade her. Return with the dagger to the gnome and he will make his way to Seawatch.
Congratulations, you now own the best castle in all of Amular.Locations for Reagents:
Seawatch is one of the best places to farm reagents once you get the castle and all the upgrades you get a massive garden with several different reagents, so just sleep in the bed at the castle and keep farming. Remember that reagents are on a 2 day respawn (Except for Seaflax which is 3 days)Seaflax
- Seawatch & Fallen Hall (End of House of Sorrows story line, about 6 can be found here.).Ysa's Breath
- Seawatch.Sativa Fibers
- Seawatch.Leechwood Bark
- Seawatch.Scarlet Flowstone
- Seawatch.Scarwood Bark
- Seawatch.Star Thistle
- Seawatch.Sky Blossom
- Seawatch.Black Cohosh
- Allestar Tower, start of the game, also found basically everywhere.White Flake
- Shardfall, top left of Cradle of Summer inside cave.Eel Petal
- Allestar Tower, at least 2 on the way to first town. also found basically everywhere.Scarab Salts
- Shardfall.Softscrabble Powder
- The Court of Winter, final warp point in the game, just warp and turn around.Cripplespore Caps
- Stonecandle Mines, first mine at start of game, also found in most caves.Edelweiss
- House of Valor, 2 inside warp point, big white bush, also all over the desert.Prismere Dust
- The Court of Winter,Red Marches & Cynic Quarry in Apotyre.
If you find this solution to be unhelpful, please tell me why in a comment and I will update it the next time I'm online.