Ooophf, hits a little too close to home
I played the entirety of Legion and BFA but, bag space is a thing… so over the years I ended up vendoring off/deleting those various BiS trinkets and socketed gear pieces as I got better gear. Little did I know or suspect those BiS items/trinkets would become must-have “mandatory” items in the future 
It’s just bad design to “require” previous expac items to defeat a miniboss. At least during the Legion MT everything was done with “current” (Legion) pieces of gear.
Guess tomorrow I’ll go back to Mechagon (BFA content) to farm up mats for a new trinket from scratch 