Zone perilous

Zone perilous was a spell that "healed" undead creatures.

Effects
When cast, the spell generated a sphere in radius. The sphere emitted a gray light and was able to penetrate solid objects and terrain. When an undead creature came into contact with the sphere, they recovered from damage inflicted upon them. The sphere drained life from any living creature except the caster. Spells of healing did not benefit a creature if they were within the sphere.

Casting
In addition to verbal and somatic components, this spell required material components, a hematite gem with a value of at least 25 gp, a bone taken from a creature that was touched by a shadow, and a single drop of water.

History
This spell was known to be used by wizards of the Cult of the Dragon.