Dark Spirit The Dark Spirit was a protean manifestation of the dark side of the Force that dwelt within the Dark Side Cave on the planet Dagobah . In the years that followed the birth of the Galactic Empire in 19 BBY , a number of individuals confronted the Spirit . Those included the Jedi Master Yoda , who faced an apparition of the Galactic Emperor Palpatine . Twenty - two years later , the young Luke Skywalker also dueled the mysterious entity during his apprenticeship under Yoda , where the Spirit assumed the form of Darth Vader , his father . History . Toward the end of the Clone Wars in 19 BBY , a lone Dark Jedi was mortally wounded after a duel with the Jedi Master Yoda . The darksider was able to retreat into a cave on the swamp planet of Dagobah , where he took his last breath . The site of the Dark Jedi ' s death absorbed their dark energies . It became the Cave of Evil and was haunted by a protean manifestation of the dark side known as the Dark Spirit . That fearful phantom was endowed with prophetic powers , and those who confronted it would learn about the darker side of their own nature . Although bound to the cave , the Dark Spirit could still roam the swamp - covered landscape of Dagobah , radiating an aura of fear and hate that could cloud the minds of most Force - sensitive individuals , thus weakening or even paralyzing them in the process . At least one other entity with similar powers was known to have existed in the Dark Force Temple located on the planet Dromund Kaas . Shortly after the death of the Dark Jedi , the autocratic Galactic Empire was formed , and Yoda chose to settle on Dagobah in order to avoid the new government ' s anti - Jedi persecutions . At some point , the old Jedi Master explored the Cave of Evil . He came to face the Dark Spirit , which had taken the form of his arch - foe Palpatine , Galactic Emperor and Dark Lord of the Sith . Immediately before his self - imposed exile on Dagobah , Yoda had fought the real Palpatine in the Grand Convocation Chamber of the Senate Rotunda , and the Jedi had been forced to flee . Now in the Cave , Yoda confronted the grinning Spirit without his lightsaber , only armed with a gimer stick . In 1 BBY , the clone of the late Galen Marek , pioneer of the Rebel Alliance , came to Dagobah with the desire to find his identity . After entering the Cave of Evil , he encountered the Dark Spirit , who took several shapes . First , the entity appeared as several " clones " of the young man , all entangled in vines and asking for help . A little further on , the spirit transformed into the captain Juno Eclipse , an old acquaintance of Marek , standing on the bridge of a ship . The clone then saw the false Eclipse getting attacked , which filled him with distress . He called out to the apparition , but both Eclipse and the rest of the vision faded all of a sudden . Two years later , the young Force - sensitive Zak Arranda accidentally led a group of cannibal younglings into the Cave . The Dark Spirit tortured them reenacting scenes of their past , when their parents were forced to nourish them upon their own flesh . By 3 ABY , Yoda had been hiding from the Empire for years . As part of his training , Yoda sent the young Luke Skywalker into the cave to confront the Dark Spirit . Upon the apprentice ' s entry , the phantom took the form of Darth Vader , a Sith Lord and Palpatine ' s second - in - command . Unbeknownst to the young apprentice , Vader had once been a Jedi Knight named Anakin Skywalker and was also his father , whom Skywalker had been led to believe to have been murdered by Vader . After a short duel , Skywalker gave in to rage and beheaded the spirit . As the apprentice watched the helmet - encased head fall to the ground , the Dark Spirit ' s armored body completely vanished in the shadows . For a moment the helmet remained on the ground completely still , then its faceplate exploded , revealing Luke Skywalker ' s own face , looking up at him . The young apprentice realized that , although that construct had been defeated , he still had much training left to do before confronting the real Vader . In no time , the ghostly vision of the decapitated head dissolved into nothingness . Powers and abilities . The Dark Spirit was able take on the form of its intended victim ' s fears or darker sides . It could move unhindered and nearly undetected through the swamp of Dagobah , only being noticed by strong Force - sensitives . In battle , the entity radiated an aura of hate and fear that could unnerve and even paralyze an opponent . Unlike Force ghost s , which were normally impalpable , the Spirit had all the appearances of tangibility for those who faced it . As Darth Vader , and Palpatine , it even used a phantom lightsaber that could cut like a genuine lightsaber . More than just morphing into a single being , the spirit could actually assume the shape of several individuals at a time and mimic entire scenes with a realistic background . It could also alter the vision that its victim had of their own appearance . Behind the scenes . In the games " " and " " , the duel with the Dark Spirit is very different for gameplay reasons . For example , Yoda takes part in the duel because two players are required in all levels . " " Game On ! " " , an article published in the " Star Wars Insider 135 " , cited the duel in the Cave of Evil with the Dark Spirit in as a possible inspiration for the fake Vaders ( Clados , Gyaos , Sasori and Wampa ) in the ambiguously canon Japanese " Star Wars " game from 1987 , who were said to have been " intended as illusions representing Luke ' s fears . " However , since those game opponents were able to kidnap Luke Skywalker ' s allies and hold them prisoner , the game contradicts the article ' s statements , since they appeared to be real creatures rather than mere illusions . In the Game Boy Advance game " " , during the Dagobah : Training portion of the Empire Strikes Back storyline , the Dark Spirit in Vader ' s appearance is encountered as a boss . However , unlike in the film , the spirit doesn ' t actually do anything and only requires a lightsaber strike to bring him down , and as such his defeat animation only depicts him keeling down and moving his arm up and down . In addition , his defeat also omits his decapitation at the hands of Skywalker .