A Doubt is a monster fought during the Dream Mentor quest in the Dream World. Many Doubts are summoned during the first battle by The Inadequacy. They represent Cyrisus, the protagonist, and his little nagging doubts about combat. Though they can be fought and killed easily, they disappear once the player defeats The Inadequacy.
It is recommended to turn off auto-retaliate to avoid attacking Doubts, and avoid attacking them at all unless using blood spells to heal.