Contrary to most libraries that Kyran visited, the one they entered was dimly lit. There were even areas that were too dark that they appeared pitch black in his view.
As per Auto-one, libraries, such as the one they entered, were present on each level of the tower. They served as a place where the participants could gather information and learn about the Ancients' different magic research and theories.
However, there is an ancient saying that warns people who seek too much knowledge, which is: If one seeks too much knowledge, the process will kill you.
The library took this ancient saying at face value because some of the books, scrolls, tablets, and memory orbs kept in that place possessed hidden dangers. The least one could encounter was being poisoned and falling into unconsciousness for a few days. What would happen to them in those days they were unconscious would be up to the participant's luck.