Legend

You land the killing blow causing the priestess to scream before slumping lifelessly to the ground, her only possession is a black book.

Demarak has been watching the whole time.

"I see you are a powerful being human. Powerful enough to take down a dark elven priestess that bound a mighty demon such as myself. Perhaps we should talk about releasing me so that I may reward you for dispatching my captor."
"You are so transparent Demarak! Don't listen to him, he's trying to trick you. He'll attack you as soon as you do it!"
"Human, I can get rid of this…annoyance that has infected your body. Azoth will always hold you back from achieving true power and ultimately he will destroy you. Release me and I will help… you have my word."
"Your word? Pah! Think about this human, have I not made you powerful? Have I harmed you in anyway? I see us as partners. Even if you don't fully trust me, at least I'm the devil you know, as opposed to the devil you don't know…"

The constant bickering between the demons is starting to take a toll on your mind, you better make a decision.