The electromagnetic torpedo was a container for Rokur Gepta's most powerful weapon.
The luminescent pale green substance contained in the torpedo was lethal to all other known forms of life. One cubic millimeter of it could destroy not only all life on a planet but all of the "organic substrate" from which any future life could come. It could thrive even in vacuum.
After completing his studies, Gepta developed the green fire to wipe out all other life on Tund, thus ensuring no other could ever learn the secret to creating it. He then created special force fields that could protect certain areas of the planet from the green flames, but even in these areas it would take billions of years for life to rise again. He used similar force fields on a smaller scale to protect himself when handling it.
During the Battle of ThonBoka, Gepta used a near microscopic electromagnetic torpedo to wipe out a large contingent of the Oswaft in order to blackmail Lando Calrissian into agreeing to his request for a duel. Little did Calrissian know that Gepta's flagship, Wennis, had orders to wipe out all life in the ThonBoka regardless of who won the duel. However, the Wennis was destroyed by Klyn Shanga and his fellow Renatasians before it had the opportunity to do so. The only place the deadly substance was known to exist after the battle was the otherwise dead surface of Tund.
The name of the technique that created the torpedo's payload is unknown, but the substance was called "green flames" or "green death" informally. Only strong electromagnetic shielding was capable of containing it.
- Jedi vs. Sith: The Essential Guide to the Force
- The Essential Atlas