Monsters

Night hags speak Infernal, Abyssal, and Celestial.

Combat

Disease (Ex): Demon fever [bite, Fortitude save (DC 18), incubation period 1 day; damage 1d6 temporary Constitution.] Each day thereafter, on a failed save, the creature must immediately succeed at another Fortitude save or suffer 1 point of permanent Constitution drain.

Spell-Like Abilities: At will - detect chaos, detect evil, detect good, detect law, detect magic, magic missile, polymorph self, ray of enfeeblement, and sleep. These abilities are as the spells cast by an 8th-level sorcerer (save DC 11 + spell level). A night hag can use etherealness at will as a 16th-level sorcerer so long as it possesses its heartstone (see below).

Dream Haunting (Su): Night hags can visit the dreams of chaotic or evil individuals by using a special periapt known as a heartstone to become ethereal, then hovering over the creature. Once the hag invades someone's dreams, it rides on the victim's back until dawn. The sleeper suffers from tormenting dreams and suffers 1 point of permanent Constitution drain upon awakening. A sleeper reduced to a Constitution score of 0 dies. Only another ethereal being can stop these nocturnal intrusions, by confronting and defeating the night hag.

Immunities (Ex): Night hags are immune to fire and cold, and to charm, sleep, and fear effects.

Heartstone (Su): All night hags carry this periapt, which instantly cures any disease contracted by the holder. In addition, a heartstone imparts a +2 resistance bonus to all saving throws. A night hag that loses this charm can no longer use etherealness until it can manufacture another (which takes one month). Good-aligned creatures can also benefit from the heartstone's powers, but the periapt shatters after ten uses and does not bestow etherealness.