Omega Serus is a planet in the Bionicle Star Wars universe and served as the location of the Sith's base from Comics 3 to 17.
Omega Serus is remote and dark with no population, making it the ideal spot for a base in order for it to be kept secret and away from any readings. There are also many caves.
The Sith base was located inside a cave, was short-lived and not much action was done other than examine data for the Sith's true plan - heading to Levanas Nui, however the Advanced Rahkshi were created on Omega Serus and a good deal of attacks against the Jedi were planned. A notable incident was when Mega Kal attacked Darth Kharahk and cut half of his arm off.
After the Sith abandoned Omega Serus, we haven't seen anything of the planet. However it is probably still unpopulated and insignificant to any activities from Jedi or Sith.