It is thousands of years in the past, four millennia before the rise of the Empire when the Jedi were plentiful. In issue #3 of
Tales of the Jedi: Dark Lords of the Sith, an ambitious Jedi named Exar Kun follows Sith teachings to the crypt world of Korriban, where the spirit of dark-sider Freedon Nadd lures Kun into the tombs with the promise of more power. Ancient mummified bodies animated by the dark side stir in the shadows, and as Exar enters the heart of the mausoleum, the walls crumble and trap Exar beneath rubble, "smashing [his] bones in a hundred places." Exar lies dying in the darkness, with the spirit of Nadd goading him.
"Your skeleton is shattered," says the spirit. "There's not much time. Do you want to live?"
And to do so, Kun essentially must make a pact with the devil. Unable to touch the light side of the Force, Kun's only avenue is to give into rage and tap into its dark side. Cursing Nadd for his betrayal, Kun accepts his power and a Sith emblem sears into the center of his forehead, branding him a Sith Lord.