A scribe can produce a random book called Rituals of the New Moon with 5 Ink of Sea + 3 Eternal Shadow + 10 Resilient Parchment. The book created is either red, white, black or grey.
The acquirer of the book is able to transform into a giant wolf for 2 minutes The colour of the wolf is determined by which book they buy: red; white; black; or grey. When transformed the user is pacified and silenced though they are able to, still do things like using or creating items.
I sell the grey book for 500 gold and the other three for 750 gold. I used to sell them for 250 and 500 gold respectively. Like all items that give me a low income I post for 48 hours. There is very little competition on my server reflecting the low demand. On my server the cost of materials is 85 gold, so thats some nice profit.
I sell one every two weeks which suggests my pricing is too high at present. I used to sell one a week at the lower prices - time to revisit those pricing levels I suspect. Every little helps.
for this and other ideas on the glyph market please follow the link to the free Croda's Inscription Gold Guide