for other ideas on the glyph market please follow the link to the free Croda's Inscription Gold Guide
This is another item i am selling more of recently.
A scribe can produce a random book called Rituals of the New Moon with 5 Ink of Sea + 3 Eternal Shadow + 10 Resilient Parchment. On my server that costs about 120gold (it used to be 85gold but costs are rising as the supply of Eternal Shadows falls). 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.
The Rituals of the New Moon can only be crafted by a Scribe. It does not drop from a mob nor can it be bought from a vendor. Scribes therefore are the sole supplier.
Furthermore, few Scribes bother to post these - making the supply very low.
Clearly, it is an item that serves no purpose other than aesthetics and yet there is demand. There is very little competition on my server reflecting the low demand – though i now sell one a day.
I used to differentiate between the books given grey is the most common but now i just sell them all for 500 gold.