Night Hag

Among the most wicked and malevolent creatures in all of Valine, night hags dwell in the Undervale. Their nightmare inducing abilities and twisted minds make them appear to be the embodiment of the ideals of the hag species.
Unrivaled in their repulsiveness, even by hag standards, describing them as ugly would be a laughable understatement, and referring to them as appearing to be old women would be an affront to the entire gender. They most resemble small, withered female trolls, but their proportions hit the eye in such a way as to inspire deep revulsion, and the uncanny way that they move - in an almost insectoid manner - makes their slow and ungainly advance deeply unnerving.
Their skin has a blue/violet hue reminiscent of a recent bruise covering their entire bodies. It can be quite light or nearly black in tone. Self-scarring in eldritch patterns, open sores and grotesque, oozing warts enhance their disgusting visage. Their unkempt, jet black hair has bones, fingers, and other bloodcurdling items woven throughout it and, unlike other hags, small horns peek out through the tangled mass.
Their pinprick pupils radiate a hellish red above their sharply pointed noses and chins. A double row of pointed fangs, coated in a foul black-tinged saliva awkwardly jut out from their cracked and torn lips.
Tempering a night hag's drive for destruction and corruption is an insatiable drive for knowledge. They can be highly informative, if equally dangerous, sources of lost secrets and forbidden lore. The safest way to interact with a night hag might well be to bribe them with information or arcane objects. Equally, striking a bargain with a night hag is a terrible idea, as they are skilled and vindictive manipulators who will sense and hunt down anyone they do business with that they sense a weakness in.
True psychopaths, night hags classify others only in terms of usefulness - with the weak being viewed only as good to be food or slaves and the strong being there to corrupt until brought down to a point where they can be food or slaves.

Culture

Shared customary codes and values

Diabolical and destructive in nature, night hags combine the insidious nature of hags with the chaotic unpredictability of demons. Night hags are very often ambitious megalomaniacs with a competing desire for power and carnage creating an endless conflict within them. However, nothing brings more satisfaction to a night hag than corrupting the pure into a perverse subversion of its former form. No bond is too sacred, no act too low and no tactic too merciless for a night hag in pursuit of bringing something pure to a twisted fall.