Door of the Sith

The Door of the Sith was a portal to the realm of, a harbor for long dead Sith spirits. In times where the current Sith needed assistance, they would call upon the dead for strength. Due to its enormous potential, it was protected by Darth Realgar on an unknown planet to the rest of the galaxy. In order to be reached, one would have to traverse through a series of mazes so numbing, the being would go insane before finishing. However, if a being was strong enough to reach the door, they would supposedly have no more strength to defeat Realgar and it would be an easy takedown for the Sith.

That was not the case in 1300 BBY, when a Jedi Knight finished the maze and reached the door. Just before his encounter with Realgar, the Knight had used a Force Restoration and Mind Strengthen, allowing him to outsmart the Sith and kill him. The Knight used the Light Side of the Force to destroy the door and the link to the Netherworld.