Great crystal

The Great crystal was a structure within the Great Temple on Korriban which contained the spirits of Jedi Masters who had been defeated by the powers of the ancient Sith. While seducing Exar Kun to the dark side of the Force, the spirit of Freedon Nadd brought him before the crystal as a final test of his commitment to the way of the Sith.

Appearances

 * Tales of the Jedi: Dark Lords of the Sith 3: Descent to the Dark Side
 * Tales of the Jedi: Dark Lords of the Sith (audio)