Plasma Enhanced by the Anti-Matter form of Spacium, the Anti-Photons were turned into Photonic Particles, causing the Plasma to become a form of Engen.
Dark Engen has an opposite charge to normal Engen, however it is more accurate to say that it is the dark counterpart of to Ultra Engen. While it may destabilize Engen into plasma and the convert it into Dark Engen, contact with Ultra Engen will neutralize both.
Due to its nature, it mutates and converts Sparks into dark versions of themselves that require Dark Engen or Deathcium to function properly. Lack of either will result in excruciating pain as normal Engen is painful to use..
Use of the substance on a dead Mechanoid, may result in a Mecha-Ghoul, a zombie like being that seeks out energy.
The wicked entity known as Lord Shiny had his Destroid followers take Dark Engen, increasing their natural aggression. After their defeat the remaining Destroids became desperate for more. Among their crimes, they also forcibly injected the substance into non Destroids to force their conversion.