1: Remember Vol'jin? He was a shadow hunter, even before the zandalari empire their ancestors used shadow magic. Shadow hunters were all both feared and respected, just like the loas. So i still think it was a loa that whispered Vol'jin, Vol'jin was Darkspear but he learnt as well shadow hunters manipulation just like the sandfury trolls, but on the hour of his death, he was too weak to understand who was speaking to him.
My idea is that it was indeed Mueh'zala. Since Vol'jin knew so much the ways of sandfury trolls, the ones that worshipped Mueh'zala, Loa of Death, maybe Mueh'zala had a certain connection with Vol'jin?
2. If Bolvar manipulated all that stuff as i saw on a leak, and made a deal with this Loa of Death Mueh'zala of any kind? Since Bolvar is where he is to protect from intruders and the ones who try to steal power to themselves, reminds me a bit Sylvanas with the Val'kyr thing in Legion? She is messing with loads of stuff and wants to steal power. Just curious.
3. Death Knights have a class campaign quest-chain to get the Four Horsemen in Legion, (which is an actual nice quest chain) and at the end "aggregates of anguish" it's a set of missions, taking you to shadowlands. They take loads of time to be completed.
You need to get essences and one of them is Shadow essence: https://wow.gamepedia.com/Unholy_Att...ence_of_Shadow
The following essences are:A manipulator and traitor, Soulbinder Nyami wielded powerful shadow magic in life. In death, she is the perfect vessel for the Essence of Shadow. Harvest the essence from her soul in the Shadowlands.
Unholy Attainment: Essence of Shadow
Unholy Attainment: Essence of Fear
Unholy Attainment: Essence of Hatred
Unholy Attainment: Essence of Undeath
Unholy Attainment: Essence of Darkness
4. Death knights are going to step up from "shadows" (lol interesting way of speaking that doesn't fit wow) and for some reason i believe this will be huge. Even Pandaren dks are supposedly confirmed, not yet from blizzard's mouth but tbh with Wowhead saying it i believe it, just like vulpera was seen by them to come. So death knights might be a gateway to shadowlands of some kind and they will be needed next expansion and Bolvar and the four horsemen will too be more present than ever. With this being said, we might see more about Kel'thuzad.Salanar the Horseman has given us a list of the remaining components. The ritual of conjuring requires five unholy essences known as the Aggregates of Anguish.
This is not at all a leak, this is a speculation thread about something i have been thinking a lot.
(Mistyped title, it's: With blizzcon coming...)