Serpent is able to describe you how to reach entrance into the caves where Demon is hiding through the day.
As you enter the cave and pas a few turns natural cave end with well crafted stone doors. Engraved atop of them is written - In Illuskan
- Bajaz translate with an effort
This is written in laguage of Ffolk who inhabit the isles. I made an effort to learn the language, but time was short. I believe it is a warning to wizard's apprentices that entering his "final tests" chambers could result in injuries and even death should apprentice be not ready or able to remember the teachings.