Paranoia is one of the last bosses to be confronted in Castlevania: Dawn of Sorrow, and is found lurking in one of the top levels of the Demon Guest House, in a section that is only accessible from the Pinnacle. In addition to this, Paranoia's arena is sealed by three walls that require specific souls to be used to allow the walls to collapse and the player to engage Paranoia in combat. The three Souls are Axe Armor, Killer Clown and Ukoback. Paranoia presents himself in two forms: a lesser Paranoia the size of Soma that suddenly bounces off the mirror in the wall of the first combat zone, and a massively oversized demon emerging from the mirror in the adjoining room.
The Little Paranoia is not much of a threat, as he can only attack with a weak stab, and if necessary, can submerge himself into the room's enormous mirror to make four floating mirrors appear, stick his hand out of one, and fire a small laser beam. This beam can be reflected by the other mirrors, a tactic that is used to ensnare Soma with more ease. The easiest way to dodge this attack to use the Bat Company soul and fly to a safe spot. When destroyed, the mirror stains with blood, and in the following room, the second and much more difficult part of the battle takes place, with a Big Paranoia emerging out of the room's mirror. This Paranoia prefers to float through the room, descending to kick or hit Soma in a twirl. He can also fire again his laser strike, only it's much more damaging than the previous one, is slightly larger, and he fires it twice in a row, rather than only once. The real problem in this battle is that he's often hard to find space from where to strike at Paranoia. When Sealed, Paranoia yields his soul, a Bullet-Type Soul that allows Soma to enter the world within mirrors.
- As it turns out, Paranoia does have a face under his mask. It can be seen (very briefly) upoon his defeat. As he is being absorbed into the Magic Seal, look at his torso: his mask flies off and exposes a vaguely human face.
- Paranoia's Soul is considered to be pretty much useless in battle. However, some of the game's hidden treasures can only be obtained by using it, so it should really be used for treasure hunting rather than combat. However, during the second battle against Dario Bossi, you need to enter the mirror in order to fight Aguni. If the player chooses to fight Dario, a bad ending is triggered.