|This article is about a/an source of power in Kamen Rider Build.|
The Nebula Gas (ネビュラガス Nebyura Gasu) is a type of gas released from cracks in the Sky Wall.
Faust is able to change people into Smash by injecting a concentrated formula of the Gas in liquid form into a test subject, exposing them to large amounts of it in gas form, or creating Smash Bottles for their agents to voluntarily use. After the contaminant elements in the gas are purified by Misora Isurugi, the gas becomes a vital component of the creation of Build's Rider System and Fullbottles. It is later learned that the gas can be further condensed into a gel for the creation of Sclashjellies.
Nebula Gas can cause the Bugster Virus to mutate into the Nebula Bugster. However, more refined samples of the Bugster virus, such as the data in the Gamer Drivers and Gashats or matured Bugsters like Parado, react negatively to Nebula Gas exposure. The Nebula Bugsters serve as the fuel for Kaisei Mogami’s inventions, namely the Enigma and the Kaiser system with its Nebulasteam Gun. Nebula Gas on its own is a powerful fuel source, as Takumi Katsuragi designed the derivative Transteam Gun to run off of it.
Nebula Gas can be neutralized by Build Genius Form.
Because Nebula Gas is a byproduct of the Sky Wall, it contains compounds not found on Earth.
When Killbas arrived in the new world and reactivated the Pandora Box by using Ryuga Banjo as a catalyst on the white Pandora Panel, those who were experimented on with Nebula Gas in the original world had their former memories restored.
Nebula Gas Gel
Phantom Liquid is a condensed form of Nebula that was created when the World of Build merged with its mirror version. It is the the most powerful form of Nebula Gas. Those who are exposed to the Phantom Liquid gain the ability to transform into a Phantom Crusher. In addition, if a person has been exposed to Nebula Gas in the past, being exposed to Phantom Liquid will allow them to transform into a Kamen Rider or Smash even if they do not currently have Nebula Gas in their bodies. Thus, the New World versions of Kazumi Sawatari and the Hokuto Sanbagarasu are still able to transform into Grease and Smash, respectively, as they were exposed to the Phantom Liquid while in a hot spring.