Maybe using it in NiM TFB causes the Dread Masters to spawn as a boss? That would be pretty rad.
EDIT: Corrected the operation name. Hurr.
Well that's assuming it's a NiM TFB mission.
From what's happened so far:
1. Patch 1.4: The Terror From Beyond
-16 Man HM has a special effect in a cave
2. Patch 1.5: Section X & HK-51
- New World Boss, Dreadtooth
i) Dreadtooth drops Dread Guard mask which protects you from "Dread Touch"
ii) 10 Stack Dreadtooth drops Amulet which summons 16 HM TFB cave enemy Dreadful Entity
ii) Dreadful Entity drops Dreadful Orb
So I'm thinking that there's nothing in Patch 1.4-6 that relates to the orb and that the Orb is 1.7 content.