I was trying to do this on an alt warlock just for fun but it seems to be broken.
I did the initial quest where you ask your minions what the tome is for, and then it popped up to start the quest that tells you to take it to a warlock trainer.
However when I clicked Accept, it didn’t add the quest to my journal, and the Tome is reset. The Tome shows a “!” But if I click on it I get a message saying “You’ve already completed that quest.”
What do I do? Is it just broken?
My alt warlock doesn’t have green fire and Kenrethad isn’t in Shadowmoon to unlock it either.
Edit: I figured it out. The quest “Reader for the Dead Tongue” that pops up after talking to your minion disappears when you try to accept it and gets moved to the warlock trainer in Orgrimmar/Stormwind. You have to accept it from them and then immediately turn it in with them.