Harvest of Souls

While only necromancers study the deep mysteries of the dead, all Void scholars are able to gain power from wandering spirits. For a period no longer than one and one-half hours after casting this spell, any shades in the same room as the caster have a chance to be consumed, providing a bonus to both hit points and mana. This effect will last for thirty hours. It is only possible to consume shades of a level equal to or less than the caster's.

While it is difficult to say for certain what, if anything a lingering shade feels, the fact that this spell cannot be used by any caster who has accrued any measure of gold aura suggests it is a highly unpleasant process.