Star Wars: A New Legacy
Athiss is located in the Outer Rim and is the second planet of the Loro Babis System. It has 2 suns and is primarily covered in jungles and wastelands.
In 137 ABY, a group of Sith researchers accompanied by Vul Isen uncovered a Sith Temple in hopes of finding answers to the whereabouts of the Telos Holocron. During their excavation, they disrupted the evil spirit of Darth Zannah.
A group of mercenaries infiltrated the temple and disposed of both Zannah and Isen. They then recovered 4 Kyber crystals for use in their lightsabers.