This item drops from Abjurist Belmara in Kirin'Var Village in Netherstorm
Belmara's Tome as a quest objective
The quest requires you to return the tome to its bookshelf at coordinates [55, 86]
. When you put the book on the shelf, Belmara will appear for a short mini-event. Once you complete the quest, Abjurist Belmara will no longer be hostile to you.