Recently hit 60 and now have a quest to collect a large amount of soul ash from Torghast (which only comes after dropping a boss). Went into on of the dungeons (the wrong one for soul ash from what I found out) but my question is on the ‘layer select’ you get when entering. One is highlighted and for me that was 1 so I just picked that one. After finding that I picked the one of the three that did not have soul ash 
I tried another and got the same option with #1 highlighted. Got my soul ash from the 4th floor (to my surprise) and decided to try the third one. Now the highlighted ‘layer’ (I am figuring that means floor) was 4th. I could still pick 1 but was afraid there would be no soul ash since I had already done 1 - 4 on the previous dungeon. I guess I need to understand how these layers (floors) work there . . .
The layers are difficulties. You need to complete a lower layer to run an higher layer.
All of them drop soul ash. You can run them as much as you like.
Layers 9 and above also drop Soul Cinders for the Rank 5 and 6 Legendaries.
Oh thanks. I also just found a good guide on wowhead and read much of what this is all about. It just leaves 2 questions. Since I have done the first layer already can I do the first layer in another dungeon and still get the soul ash or do I have to wait a week for the reset? Second since the highlighted layer is now 4 does that mean I have actually finished the first 4 layers and need to do 5 next?
Hehe that first one was the one I saw but did not read down far enough . . . seems like my best bet is just to do layer 1 once a week. Too bad the soul ash goes down with more difficult layers rather than go up . . .
Don’t think of Torghast as like a dungeon with a lockout in a traditional sense. The only thing that really changes weekly is which wings are active. The highest number you’re able to select and enter is the one you have yet to clear. So if that’s 4, then you didn’t complete a 4 yet.
Hmm so are you saying that layer 1 soul ash (180) is only obtainable once per wing regardless of the number of weekly resets? Sorry for all the question but I know nothing of the ‘normal’ dungeon world as I have not done one in over 15 years . . .
As far as I know, you can now run torghast repeatedly, even the same layer over and over for ash. It will show you the rewards on the floor select UI. If the ash is shown as a reward, even though you just did that layer, you should be able to do it again and get the ash.
Yep just found that answer " Each Torghast wing will award you a maximum of 1040 Soul Ash per week. Completing both Torghast wings will award you with a maximum of 2080 Soul Ash per week. Completing higher floors will automatically award you any Soul Ash from lower Layers, so you can skip lower floors with impunity." from one of the guides.
I’ve been running the same floors repeatedly. They used to be on a weekly lockout for soul ash. I think they changed it so you can run as much as you like now (i.e., catch-up mechanism). If you want to keep running layer 1 for soul ash, you probably could.
Cool . . . I just found out why they have less soul ash each layer. I did layer 3 of the second one for this week and got 500 some odd soul ash as it included the soul ash from layers 1 and 2 as well as 3 
Will have to check that out and see if I can do it again this week. Have they also take off the account wide nature of the soul ash? Where you could only do each wing once on one character per week.
This is outdated. There’s no weekly limit any more.
If you want to farm soul ash (or cinders), simply run the wing you can run most efficiently at the highest level practical. You just have to complete it, you don’t even have to worry about score, or clearing it all, or anything like that. Kill the boss at the end as quickly as possible and get your soul ash.
Very nice thanks!