Paradox energy
Paradox energy was an energy which saturated members of Faction Paradox. Outside of a time war, the Faction would be the only source of this energy in the universe. (PROSE: The End of the Beginning)
Siblings Different and Same found themselves in a wraith-like existence powered by paradox energy (PROSE: The Paradox Moon) amassed at the Verbier Museum of the Impossible during the Kotturuh Crisis. (PROSE: Canaries) The energy was visible in their bodies as "inky black unswirls". They used the energy to travel between timelines and build a Paradox TARDIS. After rescuing Different, the Thirteenth Doctor suggested that Different could have a normal lifespan if she didn't use the energy to create paradoxes. (PROSE: The Paradox Moon)
During the War in Heaven, the Nambiro developed a taste for paradox energy after their homeplanet was drenched in the fallout of a ruptured timeship, leading them to consume members of the Faction. (PROSE: The End of the Beginning)