Thank you!
That is a 16 on Arcana. ^_^
Aaliyah has heard a decent amount about bheur hags as they dwell in cold areas, for example, the Frostfell, the para-elemental plane of ice that exists between the Plane of Air and the Plane of Water. She might have even seen a couple in the distance flying on a magic staff away from Ishaan's palace, though I doubt she's met any in person, and is mostly going by what Ishaan and other members of the palace have told her.
Bheur hags are typically chaotic evil, and are considered cruel even by hag standards. They are attracted to selfish actions inspired by the cold, especially if said actions are unwarranted. They themselves have been known to become more active during the winter, and like to use their ice magic to make nearby settlements miserable. It is a point of debate whether bheur hags are simply attracted to the cold or if they perhaps bring the cold weather with them.
Despite their cruel personalities, however, even Ishaan has to admit they have great knowledge and wisdom, particularly when it comes to nature and survival, and people will occasionally seek them out for said knowlege.