Darth Revan's Sith Holocron

Darth revans holocron was a holocron(possibly a pyrimid shaped sith holocron) recorded by the former sith lord detailing much of his life and sith training. Revan eventually abandoned the holocron within the temple of the ancients on Rakata prime a place of great signifigence to him as it was a stepping stone on his fall to the dark side, and also the place that marked his redemption Darth Bane would later discover the holocron and use the knowledge inside to fashion the rule of two