Basphomy is the former patron of Halloween. When she ruled the Holiday, it was a day of true fear and horror. The council voted to remove her powers when she became too dangerous, and the Pumpkinheaded King of Halloween keeps the Obsidian Gate up out of fear of her. She has the power to expose her enemies to their greatest fears, as well as communicate through dreams. She is very ambitious, and helped Bun-bun kill the Pumpkinheaded King. Bun-bun feared her ambition, however, and upon acquiring godlike powers after killing Santa Claus, he trapped her and her minions in an Obsidian cage, to be released only every October 31st. It is possible that she was released when the Deus Ex Ovum was used, but this has not been confirmed.
It was revealed that she was created by Dunuloa in the Mohkadun arc, though her presence that early in time is somewhat at odds with Basphomy herself stating her time began during the events of the 2nd egg in the opening scene of Holiday Wars: Christmas arc.