A clan of Mustafarians led by Father Kkkt lived on Mustafar. After witnessing the arrival of a burning starship, Kkkt sent four of his clan to investigate where it may have landed. They discovered a dark figure, Darth vader, who killed two of them and used a haunted mask to possess another. Vader then began building a structure that could channel the Force energies from a dark side locus. This caused lava storms to erupt on Kkkt's clan. Kkkt protected them and subsequently decided to rally the other clans to destroy this structure.
Kkkt's scout party attack Darth Vader
By 12 BBY, Darth Vader traveled to Mustafar aboard a Naboo Royal Starship. He flew it through the atmosphere without the shields, causing it to burn as it soared through the sky. Father Kkkt and Zzzs watched it pass and Kkkt thought it was an omen. He subsequently sent four Mustafarian scouts on Lava fleas to find where it landed. The scout party—consisting of Bbbl, Rrrn, Sssp, and one other—found nothing when they arrived and suspected it may have dissolved in the lava. Bbbl then spotted Vader, who threw a rock at him and sent him into the lava. The other three attacked him but he cut down another Mustafarian and put a haunted mask onto Sssp, allowing him to be possessed by the Sith spirit inside.
Rrrn returned to Kkkt and described Vader to him. Soon enough, Vader and the Sith spirit controlling Sssp began building a large fortress int he Gahenn Plains, intended to channel the Force energies in a dark side locus. When attempting to use it to open the door to the dark side, the process caused lava storms to erupt all over Mustafar. Kkkt protected his clan from the lava, but as Vader and his Sith companion, Darth Momin, kept failing to open the door they tried again, and the storms got worse. Kkkt contacted other clanholds and discovered they were experiencing the same thing. He told Zzzs that it was time for them to come together and save what was left of Mustafar.
Kkkt gathers the clans to attack the fortress
Kkkt led an army of Mustafarians to attack the fortress. They outnumbered the Imperial garrison ten to one, but Vader proved a match for their numbers. Kkkt and the other clan leaders tapped into the Force and channeled a wave of lava, sweeping the battlefield clean. When Vader, the only survivor, retreated to the castle, Kkkt and his remaining forces tried to destroy it. Vader, however, channeled the Force through it and wiped out the army.
- Ultimate Star Wars, New Edition