Hex Twisting is a special book not just for Diana (who wrote it) but Nikki, who was often involved in many of the experiences and stories that led to its writing and publication. So while you will have to watch Left Unsupervised or go to a convention to hear "Diana almost killing Nikki stories," you can certainly enjoy the benefit of that hard-earned wisdom with a signed copy of this book. 
 
If you think you have anything from a hex to an entity attachment to a really angry gigantic ghost, start with Hex Twisting - Diana and Nikki dodged or befriended all the big bads so you don't have to figure it out the hard way!