The prophecy holocron was a holocron from the Jedi Order holding numerous predictions. Jedi Qui-Gon Jinn accessed it many times, and later so did his Padawan, Obi-Wan Kenobi. Several of these prophecies originated ten millennia before Jinn's apprenticeship under Dooku.
A prophecy within the holocron spoke of the Chosen One, destined to bring balance to the Force.
One prediction mentioned a "once dead" evil returning when the righteous lost their way. Many Jedi thought this referred to the reincarnation of the Sith, believed destroyed by the Jedi Order. Jedi Padawan Qui-Gon Jinn considered that the prophecy might point to the Sith Darth Wrend, thought to have died but who had resurfaced to challenge the Jedi. Ultimately, the Sith's continued existence was revealed with the discovery of Darth Maul, who killed Jinn in a lightsaber duel during the Invasion of Naboo in 32 BBY. Simultaneously, Dooku, fueled by righteous anger over corruption within the Galactic Republic, fully embraced the dark side and became the Sith's new apprentice after slaying Jedi Master Yaddle.
Jinn interpreted the prophecy of a female born in darkness who would birth darkness as referring to a Duchess of Malastare whose father was a war monger and gave birth to a daughter that became a Dark Jedi according to legend.
The holocron also held a prophecy concerning kyber crystals, stating that when the kyber that is not truly kyber is revealed, the time of prophecy would be near. During the mission to Pijal, Jinn and his Padawan Obi-Wan Kenobi discovered that Pijal's moon contained rare kohlen crystals. Jewel thief Pax Maripher explained that these were macroscopically identical to kyber crystals, distinguishable only under a microscope. This discovery of "fool's kyber" led Jinn to believe it was what the prophecy foretold, renewing his faith in the prophecies.
The prophecy holocron was already ancient when Dooku joined the Jedi Order. Dooku became fascinated by it, teaching his apprentices Rael Averross and Qui-Gon Jinn about its contents. Later, Jinn had his own Padawan, Obi-Wan Kenobi, study the holocron.
The prophecy holocron made its debut in the 2019 novel Master & Apprentice.