Tome of Binding

The Tomes of Binding drop from the following mobs in Azsh'ari Terrace in Nazjatar:
 * Azsh'ari Invoker
 * Azsh'ari Neophyte
 * Azsh'ari Oracle
 * Azsh'ari Stormsurger
 * Azsh'ari Stormwitch

As a quest objective

 * Forbidden Rituals