Heed my words, young one - there is a taint about this island, and it is far more potent than the remnants of the Scourge.
I believe there is a true demonic presence on the isle.
In exchange for your obedience, I'll teach you how to summon an imp companion - your first of many as a warlock.
The essences of the wraiths will serve me well as sources of experimentation. Much like your life as a <class>, it is important to learn from what we find in the world... before twisting it to our will. With demons as the richest source of power, it will be quite the boon if such a taint is truly present on the isle.
Well... a boon for us warlocks, that is.
Well done! Yes, this should be enough essence to get started on my research. I have a strong feeling that this tainted essence will be just the thing... the window, as I mentioned.
Following the orders of your masters is highly recommended as a young <class>. As I promised you, here is the reward for obeying instructions and completing them in a competent manner - the knowledge to summon and bind your own imp.
Use it well, <name>.