Hi! I am a PvPer, so do not know much about Mythic+ or Raiding. However, I have run VotI three weeks in a row clearing everything on my Shaman alt for the blue-tinted set and not ONE piece has dropped. I have gotten a few random things, like a staff and off-hand, but no set pieces.
Can you not solo old raids for drops? Do I need to clear VotI on Normal before Heroic? Is it normal to get no set pieces week after week?
Any advice how to collect this set would be much appreciated!
With DF drops, you just need the correct slot at the correct ilevel.
You take that piece over to the catalyst to transform it into your classes tier set.
Like, if a chest drops, you turn that into the tier set with the catalyst.
From memory, it is near Tyrhold… Really high up.
Edit: to be more specific, here are some co-ords for the DF catalyst…
/way #2025 59.8 53.7
You can farm primalist tokens from the rotating elemental storm mobs on the Dragon Isles and the forbidden reach and convert them in the catalyst for normal VoTI set. To get the heroic variant you upgrade each piece at the upgrade vendor with the untapped forbidden knowledge currency. Both are still RNG to receive the gear slots and currency drops you need and will be time consuming, but is not limited to a weekly lockout or poor drop rate from non-legacy loot like farming the raid.
Slightly more deterministic, you can purchase individual pieces with the overflow currency from Mythressa, a vendor on Forbidden Reach, but to upgrade it to the second tier (primalist tokens are automatically tier 2) you will need another currency, storm sigils. Typically, any catalyst and upgrade vendor will work for legacy gear, not just the ones in that expansion zone. You can mix and match using both options for items you are not lucky to get early on. The amount of currency needed for upgrade varies by individual piece.
So two options are:
Buy level 1 items from Mythressa with elemental overflow + use storm sigils to upgrade items to rank 2 (then convert in catalyst for normal appearance) + use untapped forbidden knowledge to upgrade to rank 3 (heroic appearance)
Learn rank 2 items from primalist tokens (convert in catalyst for normal appearance) + use untapped forbidden knowledge to upgrade to rank 3 (heroic appearance)
Here are some links for each you can investigate further:
UPDATE: I have been farming The Forbidden Reach and gotten a good amount of my pieces to drop, but no Untapped Forbidden Knowledge. Where do I farm that? Thanks!
Thanks! Sounds like a lot of work for a transmog set. I am used to just running raids each week and collecting pieces. Especially since you can now get armor pieces not tied to your class, it was a fun way to get transmogs: do a raid on my Shaman, then my Druid, and then my Hunter (my “fastest” classes), and so on. It was neat to experience the raids on different toons while collecting gear.
I am not sure I have the interest to farm Heroic VotI gear as it sounds like it involves a lot of farming outside of the raid, but I will use the links you provided for more research and I really appreciate the detail of your post! 
You’re welcome! I’m glad I could help. I seem to recall a decent way to farm was to summon the profession rares on the island. You don’t have to have each profession, but can buy the items on the auction house and go to each summoning location. Check this link at the bottom they list all the profession rares and curios needed:
Alternatively when the next expansion comes out and you are at least level 81, those raids will be eventually converted to legacy loot and you will have a much better time farming that way. I get so much from the Shadowlands raids now. I finished with a full set on one character after a SOTFO run recently and got several tokens for alts. If you can be patient to wait it will get easier over time. I think it’s nice to have multiple options!
Hi! I wanted to follow-up, because nobody seems to do that unless it’s a negative situation, and say that your advice was amazing: plus one internets for you! I have all of my set gear that I want from EASY farming on The Forbidden Isle for my Normal (Brown) and Heroic (Blue) sets and have upgraded them with the Untapped Forbidden Knowledge drops from rares and chests on the isle.
The only pieces I am missing are truly boss drops. I really HATE that most caster (Cloth, Mail, Leather, and Plate) sets are “robes” in design. Who tf wants to cast spells and run in a robe in PvP? No that I’m a role player, but come on, that’s a dumb fantasy concept (to me) lol!
Anyway, I just need a chest piece (in both Normal and Heroic: Embar’s Ashen Hauberk) to complete my sets (i.e. a chest piece instead of a robe). However, in the meantime, there is an alternate piece of gear that fills the slot nicely and I have it.
You are amazing, you are awesome, and I greatly appreciate your input on my quest for this transmog (which was wildly quicker than I anticipated, minus the non-set pieces).
Thank you so much for coming back to give an update and for your kind words! I’m really glad you were able to get most of what you were looking for. I don’t come around the forums nearly as much as I used to, but makes it feel worthwhile to know I helped at least one person out there. 
I’m still missing a handful of appearances from there, so it’s good to know it’s not a terrible grind nowadays. Cheers to you and happy mog farming!