So. Obviously I grabbed this one since it deals with darker magic and was part of the Haunted Highlands campaign (which I also enjoy). There is also the cover which is a call back to the infamous Eldritch Wizardry of OD&D.
The first part covers necromancers and necromancer spells. This includes a way for normal spell casters to gain a level of Necromancer. A nice little add on for any CK really.
There is also a great spellbook in here called the "Grimoire of the Witch Queen" that makes the whole book worth it to me all by itself!
That's the first half of the book. Later we get into Ritual/Sacrificial magic, magic items and some new monsters. Given the types of games I run and the magic I like to have this is a "Must Have" book for me. The book is a tight 38 pages.