When it becomes undead, a king-wight gains many special abilities. A successful attack can drain two life levels from a victim, as per a vampire. Any victim completely drained of life points by the kingwight becomes a full-strength wight under the control of the king-wight.
A king-wight also has the ability to cast spectral force and confusion spells, one spell per round, without limit. It can teleport once per day, but only to or from its barrow home.
When the king-wight is destroyed, the action causes an earthquake (as per the clerical spell, at the 14th-level of effect), centered on the king-wight's body, in 4-16 rounds. Since a king-wight is often encountered in its underground barrow, such an earthquake can be especially deadly.
A king-wight is so powerful that any individual of a level lower than the kingwight must make a saving throw vs. spells or flee in panic from fear.
The following spells or attack forms have no effect on a king-wight: charm, sleep, enfeeblement, polymorph, cold, electricity, insanity, and death magic. A raise dead spell turns the king-wight into a normal 12th-level fighter unless a saving throw vs. spells is made.
When the king-wight is destroyed, the action causes an earthquake (as per the clerical spell, at the 14th-level of effect), centered on the king-wight's body, in 4-16 rounds. Since a king-wight is often encountered in its underground barrow, such an earthquake can be especially deadly.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.