Odd, possible reference to Halaster?

[Halaster Blackcloak]

I was reading through the FR 1E Gray Box set and I noticed something I never put together before. In the DM sourcebook, on pg. 64 where it details a magical book called the Chambeleon, it mentions the Mad Mage and his apprentice named Arbane. The texts says that the "Mad Mage" may have bound a demon to the book to serve as a guardian. It also says the "Mad Mage" made reference to the spells imprisonment and prismatic sphere, so that would indicate a higher level wizard of at least 18th level. Hmmm. Interesting. Considering the box set came out 4 years before Ruins of Undermountain, I wonder if it has any significance?

[McDeath]

Seems fair. Just research mentions of those beings and objects if any is to be had.