Subconscious and dreams spill over into woken thoughts; The deluded character sees a different reality, and cannot control when it intrudes upon the real one. Delusional characters become convinced of something which has no basis in reality but informs every aspect of how they perceive the world around them. It is a powerful form of altered perspective which can be self-imposed or an effect from some condition or power.
Disadvantage on all Wisdom (Perception) checks; -1 on all Saves and Attacks. Any Fumble result automatically triggers secondary effects (drop weapon, hit ally nearby, etc.).