Vampiric Youthfulness

With this spell, the caster makes himself younger by leeching the life energy out of another creature. The victim must have Hit Dice or levels at least equal to the caster's level, and must be at full hit points at the time the spell is cast. Undead, extraplanar beings (such as elementals) and non-corporeal creatures cannot be affected by this spell. A charmed creature will not willingly submit to this spell, though a creature under the effects of a domination spell will; even a willing victim is allowed a saving throw to negate this spell. The caster and the victim must be touching for the entire casting time of the spell; any interruption negates it.

Once cast, the subject creature ages 10 years immediately. A creature aging beyond its normal life span, dies; otherwise, it remains unconscious for 24 hours. The creature suffers any aging effects upon regaining consciousness. The caster becomes one year younger. Present damage is not healed, nor are curses or diseases removed. The caster retains all memories and experience.

Performing this spell on an unwilling victim is definitely an evil act and cannot be undertaken by a good character, even against an evil victim. However, a good character might use this spell when a subject creature is willing and has plenty of years to spare.