I recently got the mythic warlock robes from Abberus and lost the roll for the shoulders. I was bummed so I tried to play around with different shoulders and come up with something and I accidentally stumbled onto a really good transmog that I love, so I wanted to share it.
This is the set 
I absolutely love it. It fits undead so well. The collar on the robe is my favorite part. The set overall isn’t even made up of a matching set.
Chest: Abberus (mythic recolor)
Shoulder: Shadowlands covenant cosmetic set (Maldraxxus)
Gloves/Cloak: Amirdrassil (mythic recolor)
Belt: Antorus (normal)
Boots: Dreadlord store set (even though you can’t see them)
Staff: Destruction hidden artifact (purple version)