Lux Haeresis

Once again, the wonderful folk (Daniel Schulke) at Xoanon have been perpetrating their own particular brand of Spare-ist confusion, this time resulting in the lovely shimmering gray LUX HAERESIS. If you go to the source, you may be able to find a copy for $100 plus shipping.
Like its forebears, this is no easy read, as the author loves writing in strange words. Something charming in "the Focus of Life" and "The Logomachy of ZOS", it is a habit that can get tedious when handled by lesser people. The late Andrew Chumbley was a master, where it comes across as a mask to hide the light from the unworthy, but for lesser mortals like Pharaon and others, it can come across as derivative and childish. Schulke treads a middle zone, sometimes getting it right, and sometimes appearing pretentious.
However, language aside, Schulke continues a very valuable tradition, that of the Cultus Sabbatai, which is more of a successor to Austin Spare than the late Kenneth Grant ever was with his qlippothic typhonian OTO - largely an exercise in turgidity.
There are few people out there who cater to intelligent adults, and Cultus Sabbatai is about the only one that I'm aware of (Clearly, I dont get invited to the right sort of parties). The rest are either PC or reactionaries with the mindset of rebellious teenagers.
My greatest regret is that Cultus Sabbatai is a closed order, so you can look but not touch (i.e., read, but not participate).

Unfortunately I cant recommend this book as a practical guide, anymore than I could the works of Austin Spare, due to the language barrier. However, it is a worthy grimoire, few indeed of which are being published these days. If you enjoy well-made books that are classics, and have the money available for this kind of purchase, I recommend buying a copy today, before it sells out and prices start escalating. Contact the publisher at the snailmail address they use, and take it from there, or find a good bookseller (they recommend Field's books in SF or Caduceus in the UK, both of whom I would also recommend) and pay a little more.

In rank, I'd place this after Azoetia and Viridarium Umbris, but before Ars Philtron which appeared somewhat clumsy by comparison (if more practical).