If you want to make a Shadehound to ride in the Maw, you need to gather Stygia Dust. But where is it? I'll show you.

Step 1: buy a Stygia Dowser from Ve'nari. Green glowy Stygia Nexuses will show up on your map.

Step 2: gather enough Stygia Dust and Silver to make 20x Stygia Bar.

Step 3: buy a Partial Rune Codex from Ve'nari.

Step 4: go find 3 Rune Pages which will now show up on your map.

Step 5: loot the Soulforger's Tools from Soulforger Rhovus

Step 6: assemble the Armored Husk at the Soulsteel Anvil on top of Domination Keep

Step 7: find a Stray Soul in the River of Souls

Step 8: bind the soul to the armored husk at the Binding Altar

Step 9: ride the feral shadehound and use the runes in your actionbar in the order your codex says

What else might help me find things?

Handy Minimap Arrow will make your player-arrow on the minimap appear *above* all the notes I'm adding to it
What's On The Map? will show a list of the vignettes currently up nearby
Minimap Range Extender will make map vignettes visible from further away
HandyNotes: Shadowlands Treasures (and rares) will show you all the other stuff in the Shadowlands

HandyNotes: Stygia