Samuro's holocron
From Wookieepedia, the Star Wars wiki.
Samuro's holocron was a holocron made by Samuro. The Jedi Knight sacrificed himself to imprison energy vampire Countess Rajine many centuries before the Clone Wars with the Force.
Knowing that his power would not last forever, the Jedi used his holocron to record the means with which another Jedi could one day finish the task he started and destroy Rajine's evil.
Samuro died entrusting the holocron to his droid, Z-18 who would later pass on the cube to Mace Windu who had come to the planet looking for Alpha-2 Squad. Windu activated the holocron before Raije and Samuro appeared. Together the Jedi spoke the words of banishment which turned the vampire's zombie slaves against her to finally defeat the Countess once and for all.
