The Halloweenja is the Norrisville Ninja's suit infused with Halloweenja The Essence of Terror. This power that can be added to the suit can be found in the NinjaNomicon's The Forbidden Knowledge of the Shadow Warrior.
The Halloweenja can use a stank-like mist to turn inanimate objects or people into monsters, often pertaining to what they look like or what they're dressed up as. However, the Halloweenja is a difficult power to control. The suit can become conscious and spit out the user of the suit. With its mist, it can control its transformed minions and desires to attack and cause mayhem.
The Halloweenja has no effect on things that are cute. If its minions are hugged or in contact with anything adorable, they revert back to normal. Also, the only way to completely get rid of the essence of terror from the suit is to open the NinjaNomicon nearby, which sucks up the terror.
- Summoning the Halloweenja is the second ability that Randy has accessed from the Forbidden Knowledge of the Shadow Warrior, the first ability being the Art of Healing.