A Jedi Holocron came into existence when Samuro, a Jedi Knight, gave his life to trap the energy vampire Rajine (also known as the Countess) utilizing the Force. This event occurred many centuries prior to the Clone Wars. Realizing his power had limits, the Jedi employed his holocron to document the method by which a future Jedi could complete his mission and permanently eliminate Rajine's malevolence. Samuro passed away, leaving the holocron in the care of his droid, Z-18. Subsequently, Z-18 transferred the cube to Mace Windu, who had traveled to the planet in search of Alpha-2 Squad. Windu then activated the holocron, causing Rajine and Samuro to manifest. United, the Jedi recited the words of banishment, which incited the vampire's zombie thralls to turn against her, resulting in the final defeat of the Countess.