Christmas Spirit is a powerful green substance first introduced in The SiIvaGunner Christmas Comeback Crisis. Produced by Santa Claus through worldwide appreciation of Christmas, Christmas Spirit imbues whomever receives it with immense power.
President Haltmann, the assistant of the Voice Inside Your Head, documented the history and characteristics of Christmas Spirit in Christmas Spirit [FILE-07] - Haltmann's Archives. Christmas Spirit was first discovered by the Haltmann's Patrol Bots in a production facility in the North Pole. Based on Haltmann's findings, Christmas Spirit is highly volatile and makes a sleigh bell noise. Santa likely used the Christmas Spirit to give himself superhuman strength as well as augment his weapons, such as the bombs he used in the 2002 Iraq bombing. It was found that Christmas Spirit could be obtained by festive activities, including the production of high quality rips.
During The Christmas Comeback Crisis, the Voice sought to attain Christmas Spirit in order to fuel his takeover of Grandiose City. To meet this end, he put SiIvaGunner in an eternal sleep with a mind-reading helmet in order to harvest the Spirit from his dreams, put JustinRPG in charge of a facility to produce artificial Christmas Spirit, and captured Santa Claus, holding him captive in his own workshop. However, Smol Nozomi and Meta Knight found Santa captive in Advent of Hell (Episode 6) and freed him. After this, Santa destroyed his workshop in order to prevent the Spirit from falling into the wrong hands. However, he kept several vials of it as backup in case things went awry.
However, Angry Joe also obtained a vial of Christmas Spirit, which he gave to the Voice. Later on, Joe fought Nozomi's Smolitzer in his own robot, the Mecha-Dick MK-II. The Mecha-Dick pummeled the Smolitzer, forcing Santa to use one of his vials to power it and destroy the Mecha-Dick. But in their second encounter, Joe used his own vial given by the Voice in order to empower himself and knock out almost everyone, though Nozomi and Snoop Dogg still managed to defeat him.
When entering the Voice's tower, now taken over by Haltmann, Nozomi, Santa, and Meta Knight fell into the Voice's secret lab, where they found large vats full of artificial Christmas Spirit. They also found JustinRPG, who planned to use the Christmas Spirit and bring his true love, Reshiram, to life. The Voice, still present in the castle, spoke to Justin through an overhead speaker, disapproving of Justin's actions but allowing him to create Reshiram anyway. However, upon her creation, Reshiram ate Justin, forming a hybrid monstrosity known as Ju'Reshoggoth. Ju'Reshoggoth ripped of Santa's arm and knocked out Meta Knight, but before it could kill everybody, Santa used all his remaining Christmas Spirit and finally killed the monster.
In The Lost Rip - A SilvaGunner Christmas Comeback Crisis Side Story, The Voice's other way of manufacturing Christmas Spirit (harvesting it from SiIva's dreams) took a disturbing turn when SiIva, now asleep for almost two years, started to have nightmares instead. This caused SiIva to produce the powerful substance known as Halloween Spirit, which possessed and killed many (including Haltmann, the Voice, Nozomi, Santa, and Meta Knight) before finally being stopped by Wood Man, Reader, and a now-reawakened SiIvaGunner (although it is unknown how canon this event is).