On PTR 5.2, the Sealed Tome of the Lost Legion drops from the Green Flame Infernal (Test Realm Inhabitant) which is located east of the Shado-Pan Garrison. Only for testing purposes.
Warlock players must create a Healthstone, then click on the Sealed Tome of the Lost Legion to combine it with the Healthstone to bind the tome to yourself. Requires level 90.
Combining both creates “The Codex of Xerrath”. This item begins a quest titled “An Unusual Tome”.
An Unusual Tome
The Codex of Xerrath: The tome appears to be written in an ornate, sprawling script that seems to rise off the pages. It vaguely resembles Demonic, but the symbols are far more elaborate than any you’ve ever seen.
Perhaps one of your demonic companions can tell you more.
Objectives
Speak with your demonic minion to determine the origins of the tome.
Progression
Note: A dialogue bubble appears above the Warlock pets.
Voidwalker: Dismiss me … I wish to return to the void.
(You: What can you tell me about this tome?)
Voidwalker: Words are not the way of the void. I do not know … it appears to connect two … stars together.
(You: Fascinating …
Imp: Yea? Sup, boss?
(You: What can you tell me about this tome?)
Imp: Hmm … I have no idea.
Succubus: Hello Master … what kind of service can I provide you today …?
(You: What can you tell me about this tome?)
Succubus: What? You just want me to look at some dirty old tome? Ugh, how disappointing.
This is the script of the Nathrezim, what you call Dreadlords. They rarely use it outside of their home.
(You: Fascinating …)
(Determine the language of the tome: 1/1)
Completion
The codex appears to be a powerful tome written in an ancient, pre-demonic tongue. You strongly suspect this should be brought to the attention of the Warlock trainers in your capital city.