Following the Battle of Endor, Dark Lady of the Sith Lumiya and her then-apprentice Carnor Jax undertook a mission to Bosthirda. There the Sith tracked down the Prophets of the Dark Side, who only moments before had been significantly reduced in number by the Dark Jedi Azrakel. Lumiya and Jax slew the survivors.
Sources[]
Evil Never Dies: The Sith Dynasties on Hyperspace (backup link) (original site is defunct) (First mentioned)