Unidentified Sith holocron (Umbara)

This Sith holocron was owned by a member of the Dark Acolytes using the Umbara Sith Academy during the Battle of Umbara. A Jedi Knight defeated this acolyte outside the academy and inserted it into a shape in the door of the academy. The door opened and the knight entered, defeating Varad Zagg and many Dark acolytes. The knight also defeated the brothers Darth Maul and Savage Oppress, although they escaped.

Behind the scenes
The Sith holocron appeared in "Star Wars: Clone Wars Adventures (video game)". It could be obtained by killing several Sith acolytes outside the Sith Academy, getting a shard of the holocron every time. Once you have all the shards, the holocron will be given to you. It is required to enter the Sith Academy, and can also be placed in any of your houses as a holocron floating above a pedestal, giving off black smoke.