Nkllonian lava extract was an illegal drug at the time of the Galactic Empire. Extracted from the metal xonolite consumed by Mustafar's Jawenko lava beast, the drug was often transported to Nkllon, where it became an underworld craze.
When taken, the Nkllonian lava extract entered the user's bloodstream and liquefied their internal organs. If one used one hundred percent of it at once, they would spontaneously combust. This deadly side effect was famously revealed when it happened to a male Balosar from Coruscant.
- Underworld Appendix: Swoops, Spice, and Wretched Rogues on Hyperspace
- The Complete Star Wars Encyclopedia