D&Dtools1

This spell drains away a portion of the negative energy that keeps an undead creature animated, transferring it to you in the form of temporary healing. The spell deals 5 points of damage per caster level (maximum 100 points). At the same time, you gain temporary hit points equal to the damage dealt, up to a maximum equal to the current hit points of the target. For example, a 13th-level cleric would normally deal 65 points of damage to an undead creature. However, if that creature had only 48 hit points remaining, the caster would gain only 48 hit points (even as the target was destroyed). These temporary hit points last for 1 hour. A successful Will save halves the damage dealt and the hit points gained.

This spell is often cast on willing undead to aid their living masters. Nonintelligent undead cannot be commanded to voluntarily fail their saves or lower any spell resistance, but intelligent undead can be.

Arcane Material Component: A handful of dead cockroaches.