Ghosts are the spirits of humans who were either so greatly evil in life or whose deaths were so unusually emotional they have been cursed with the gift of undead status. Thus, they roam about at night or in places of darkness. These spirits hate goodness and life, hungering to draw the living essences from the living.
As ghosts are non-corporeal (ethereal), they are usually encountered only by creatures in a like state, although they can be seen by non-ethereal creatures. The supernatural power of a ghost is such, however, that the mere sight of one causes any humanoid being to age 10 years and flee in panic for 2-12 (2d6) turns unless a saving throw versus spell is made. Priests above 6th level are immune to this effect, and all other humanoids above 8th level may add +2 to their saving throws.
Any creatures within 60 yards of a ghost is subject to attack by magic jar. If the ghost fails to magic jar its chosen victim, it will then semi-materialize in order to attack by touch (in which case the ghost is Armor Class 0). Semi-materialized ghosts can be struck only by silver (half damage) or magical weapons (full damage). If they strike an opponent it ages him 10-40 (1d4x10) years. Note that ghosts can be attacked with spells only by creatures who are in an ethereal state. Any human or demi-human killed by a ghost is drained of its life essence and is forever dead.
If the ghost fails to become semi-material it can only be combatted by another in the Ethereal plane (in which case the ghost has an Armor Class of 8).
Ghosts can be turned by clerics after reaching 7th level and can be damaged by holy water while in their semi-material form.
In most cases, a ghost is confined to a small physical area, which the ghost haunts. Those who have heard stories of a haunted area can thus attempt to avoid it for their own safety.
A ghost often has a specific purpose in its haunting, sometimes trying to "get even" for something that happened during the ghost's life. Thus a woman who was jilted by a lover, and then committed suicide, might become a ghost and haunt the couple's secret trysting place. Similarly, a man who failed at business might appear each night at his storefront or, perhaps, at that of a former competitor.
Another common reason for an individual to become a ghost is the denial of a proper burial. A ghost might inhabit the area near its body, waiting for a passerby to promise to bury the remains. The ghost, in its resentment toward all life, becomes an evil creature intent on destruction and suffering.
In rare circumstances, more than one ghost will haunt the same location. The classic example of this is the haunted ship, a vessel lost at sea, now ethereal and crewed entirely by ghosts. These ships are most often encountered in the presence of St. Elmo's fire, an electrical discharge that causes mysterious lights to appear in the rigging of a ship.
In many cases, a ghost can be overcome by those who might be no match for it in combat simply by setting right whatever events led to the attainment of the ghost's undead status. For example, a young woman who was betrayed and murdered by someone who pretended to love her might be freed from her curse if the cad were humiliated and ruined. In many cases, however, a ghost's revenge will be far more demanding, often ending in the death of the offender.
The dreadful fear caused by the ghost, which ages a victim 10 years, is not well understood by the common man, who often ascribes it to the fact that a ghost is "dead." If this were the case, then certainly skeletons and zombies would have the same effect, which they do not.
Common folklore further confuses this fact by relating details of the ghost's physical form: the classic example of which is the headless horseman, thought by many to be particularly frightening simply because he had no head. Under this belief, one could face a ghost if only one had the courage to stand up to him. Such a mistaken impression has cost many lives over the years. Actually, the fear is caused by the supernatural power of the ghost, and has nothing whatsoever to do with courage.