Commentary On The Otherworldly Aspects of The Shadowlands (Arduin Grimoire volume 7) By David E. Hargrave

 "This, the seventh volume of the Arduin Grimoire series, begins with a tour of the infamous Great Wurm Road and takes you beyond the Ebon Gates of “Lost Shamballah” into a bizarre alternate dimension known as the “Shadowlands”. Along the way, you learn more of Arduin’s ancient myths and legends; discover more of Arduin’s unique gems and jewels; meet the mysterious Pandha-Ha (A new character race); and learn about the mystical Soothsayers (new character class)."

"This tome also presents new Rune Singer and Rune Weaver magiks; details on “Demon Magik” and “Psi-Rogue” characters; new Thief and Courtesan encounter charts, special abilities for “really nasty” characters, more orc alchemy, new herbal concoctions, Arduin Techno weapons and other technological doo-dads,. And of course, a new assortment of monsters, treasures, spells, magik items and potions. "

Shadowlands (Arduin Grimoire volume 7) is rife with the otherworldly aspect of the Arduin planes. The Ebon Gates of “Lost Shamballah" is dead on as an otherworldly dangerous location. 
The Great Wurm Road is sorta like the Underdark of Arduin only much more alien. The  Great Wurm Road are an underground adventure route  is filled with ancient ruins, dungeons, & other world locations. The place is a by road for ancient Arduin monsters, and strange monsterous races. 
The Shadowlands is an alternative dimension to Arduin &  dangerous on its own terms. This other plane adventure locotion is rife with possibilities.

The Shadowlands is only part of this book. There is demon magick, Rune magicks, & dragon magicks. This ties into some of the Arduin magicks that we've seen in the other Grimoires. Demons are rife on the outer edges of Arduin's campaign. The magicks of Arduin are powerful & intrinisically a part of of the campaign. 

The demon magick reminds me of some of the demons that we find in Advanced Dungeons & Dragons Fiend Folio. Ancient evils that have powerful magicks waiting to take victims.