Stokia was an especially adept Bene Gesserit sister who was trained to be a guilt-caster. Stokia would sneak up behind her victims, when ordered by the Sisterhood, and diable them with psychic waves of energy. Coupled with Stokia's bringing up the great disappointment that the Sisterhood felt in the intended victim, the victim would soon be rendered comatose; and en-wrapped in their own guilt.