Regenerate

When a regenerate spell is cast, body members (fingers, toes, hands, feet, arms, legs, tails, or even the heads of multi-headed creatures), bones, and organs grow back. The process of regeneration requires but one round if the severed member(s) is (are) present and touching the creature, 2d4 turns otherwise. The creature must be living to receive the benefits of this spell. If the severed member is not present, or if the injury is older than one day per caster level, the recipient must roll a successful system shock check to survive the spell.
The reverse, wither, causes the member or organ touched to shrivel and cease functioning in one round, dropping off into dust in 2d4 turns. Creatures must be touched for the harmful effect to occur.

Reversible

Sphere: Necromantic
(Necromancy)

Range: Touch
Components: V, S, M
Duration: Permanent
Casting Time: 3 rounds
Area of Effect: Creature touched
Saving Throw: None

Material Components: a prayer device and holy water (or unholy water for the reverse)