Bestow Dying Curse

In order for this unusual ability to function, the necromancer must have suffered direct physical harm as a result of another creature's willing actions. Once wounded for 1 hp of damage or more, the necromancer can pronounce a dying curse on up to one creature per level of experience, providing the victims are within 200 yards of the wizard. The curse only takes effect once the necromancer dies, and it can be used as an “insurance policy” to ensure the wizard's survival. Declaration of a dying curse is always made in a grand, theatrical gesture (it has little effect as a deterrent if the victims are unaware of its power).
Normally, there is no saving throw to avoid this sort of curse's effect, as the victims willingly accept the curse when they destroy the necromancer (it's the price that they pay). If the wizard does not pronounce the curse before his or her death, then the victims may be entitled to a save vs. spells (–4 penalty). The curse is permanent unless reversed by a wizard or priest of greater level than the necromancer that bestowed it.
The new RAVENLOFT boxed set contains a whole chapter on the subject of inventing creative curses for the campaign (Realm of Terror booklet, pages 54–65). At the very least, a dying curse may be similar to the afflictions outlined in Chapter Three or like the spells bestow curse or plague curse. The dying curse should be tailored by the DM to suit the mood and personality of the necromancer. Note that a dying curse, when fatal, does not necessarily slay the victim quickly or painlessly. It can be a slow, excruciating process, similar to the effects of a cause disease spell or mummy rot.