The holojournal of Klias Teradine, a Padawan of the Jedi Order during the High Republic Era, recounts that the Sith Lord Darth Krall subdued the entity known as the Nightmare Conjunction. In 231 BBY, Jedi Master Estala Maru accessed ancient records from the High Republic Era that mentioned the Mulita system and dated back to the days of the Nightmare Conjunction. Later, in 88 BBY, Sifo-Dyas, then a Jedi Initiate, came across Teradine's journal and shared its contents, including the tale of the Nightmare Conjunction, with his friend, the Initiate Dooku.
Reportedly, Darth Krall, a Sith Lord who had previously been a Jedi Master before succumbing to the dark side of the Force, is said to have brought the Nightmare Conjunction under control. This account of Krall's control over the Nightmare Conjunction is documented in the holojournal penned by Klias Teradine, a Jedi Padawan during the High Republic Era. Teradine met his death in 241 BBY at the hands of Tylera Yorrick, a fellow Padawan, after Teradine was possessed by a vitalicron. However, many Jedi later theorized that he had been expelled from the Jedi Order. By 231 BBY, ancient records from the days of the Nightmare Conjunction mentioned a star system called Mulita.
While searching for information on Mulita in 231 BBY, Estala Maru, a Jedi Master, accessed the primary archive located on the planet of Coruscant. He discovered that the system was mentioned in records dating back to the time of the Nightmare Conjunction. In 88 BBY, the holojournal of Teradine was discovered by Sifo-Dyas, then a Jedi Initiate, revealing Krall's subjugation of the Nightmare Conjunction. Sifo-Dyas shared this information with Dooku, a fellow Initiate, who subsequently informed his sister Jenza about these events in a holo-letter. Around 23 BBY, Dooku provided data disks containing these messages to Jenza to Asajj Ventress, his recently recruited Sith assassin, as part of her investigation into his sister's location, and she listened to the message that mentioned the Nightmare Conjunction.
The initial mention of the Nightmare Conjunction occurred in the audio drama Dooku: Jedi Lost, authored by Cavan Scott and released on April 30, 2019. The spelling of the name was subsequently verified with the publication of the script on October 1 of the same year.