The Cave of Evil, alternatively referred to as the Dark Side Cave, was a cavern situated on Dagobah and it contained a potent dark side manifestation of the force.
This limestone and dirt cave, known as the Dark Side Cave, was buried deep within the equatorial swamps and housed a vergence in the Force, as well as the specter of a dark jedi. The cave served as a central point for the dark side of the Force, testing the perceptions of all who dared to enter. Enticing visitors, it frequently induced visions of past, future, or potential future events.
Centuries prior to the advent of the Clone Wars, the Jedi Master Minch engaged in combat with and ultimately vanquished a formidable Bpfasshi Dark Jedi leader. The dark jedi's energies seeped into the cave's environment, thus contaminating it with the Dark Spirit.
During the Clone Wars conflict, Yoda experienced a vision of the Dark Side Cave while meditating. In this vision, Qui-Gon Jinn had survived the Battle of Naboo and had taken a nine-year-old Anakin Skywalker as his Padawan. He guided Skywalker into the cave to confront his fears, imparting the same wisdom that Yoda would eventually convey to Anakin's son, Luke, many years later, including the statement that all that resided within the cave was "Only what you take with you." Later, as the Clone Wars neared their conclusion, Yoda himself ventured into the cave, guided by Qui-Gon, who had learned to communicate from beyond the grave. There, Yoda witnessed visions of the Jedi Order's downfall and the ascent of Darth Sidious.
During the era of the Great Jedi Purge, Yoda came to the realization that being in close proximity to the Dark Side Cave could help to diminish his strong light side Force presence, thereby preventing detection by the Sith. Consequently, he established his residence near the cave, remaining there for the subsequent two decades throughout the reign of the Galactic Empire. Shortly after his exile, an Imperial scout by the name of Keog Boorn investigated a signal originating near the cave. Yoda, concealed from view, observed the scout's departure after he recalled the Bpfasshi Dark Jedi and heard unsettling noises. Keog Boorn then departed from the planet and reported that Dagobah held nothing of interest, attributing the signal to an atmospheric anomaly.
As the Rebellion began to form, the clone of Starkiller engaged in a brief conversation with Yoda before entering the cave in pursuit of the answers he sought. Once inside, he found himself unable to utilize his Force abilities, with the exception of the mind trick, which he employed on several occasions. He confronted the Dark Spirit, which manifested in the form of multiple other clones of Starkiller, and had to carefully navigate a series of deep chasms. Ultimately, he ventured deep into the caves and received a vision of the assault on the Salvation. Starkiller then exited the cave and departed from the planet.
In 1 ABY, the young Force-sensitive individual named Zak Arranda inadvertently guided a group of cannibal younglings into the Cave. The Dark Spirit subjected them to torture by reenacting scenes from their past, specifically when their parents were compelled to nourish them with their own flesh.
When Luke Skywalker journeyed to Dagobah to undergo training with Yoda in 3 ABY, the elder Master assigned him the task of entering the cave. Luke encountered the Dark Spirit, which assumed the form of Darth Vader, and engaged it in a lightsaber duel, momentarily succumbing to the dark side's passion during the confrontation. It was during this encounter that he grasped the potential consequences of yielding to the dark side of the Force. Behind Darth Vader's mask, he beheld his own face. This also foreshadowed the revelation, unknown to him at the time, that Vader was, in fact, his father, Anakin Skywalker.
Five years following Yoda's death, Luke Skywalker made a return trip to the cave. On this occasion, he experienced a vision of a possible past, in which Mara Jade accompanied Jabba the Hutt's entourage to the sarlacc. She managed to seize Luke's lightsaber from him before his vision abruptly concluded. While within the cave, he discovered a beacon left behind by Jorj Car'das. In 14 ABY, the Disciples of Ragnos drained the dark side power emanating from the cave. This action supposedly eliminated all of the dark energy, but it is presumed that it eventually returned to its source upon the destruction of the Scepter of Ragnos or through some form of regeneration. In 22 ABY, Anakin Solo, Tahiri Veila, and Uldir Lochett ventured into the cave after Anakin experienced a recurring nightmare of transforming into the infamous Darth Vader. Inside, Tahiri encountered a vision of her parents and grandfather, while Anakin confronted manifestations of his own uncertainties. Both emerged victorious from their trials. Uldir, who lacked Force-sensitivity, encountered nothing within the cave but sheer emptiness. Other Force-sensitive individuals who entered the cave included Tash Arranda and Zak Arranda.
Star Wars Infinities: A New Hope, while classified under the Infinities banner, posits that the cave's corruption occurred approximately eight centuries before the Battle of Yavin.
Vision of the Future recounts how Jedi Master Yoda engaged and defeated another powerful Bpfasshi Dark Jedi within the confines of the Cave. However, in Star Wars Insider 98, Leland Chee clarifies that this is no longer considered canonical, as Yoda had never set foot on Dagobah prior to his exile. The notion that Yoda had never visited Dagobah before his exile was subsequently and directly contradicted by "Voices," an episode of the CGI animated series Star Wars: The Clone Wars, which revealed that Yoda had, in fact, journeyed to Dagobah, summoned there by the spirit of Qui-Gon Jinn to gain knowledge of the path to immortality.
In the Dagobah map featured in Battlefront II, the cave serves as one of several command posts. Within its confines, players can discern the distinct breathing sound of Darth Vader.
In The Story of Starkiller, a video documentary delving into the Star Wars: The Force Unleashed II video game, it is disclosed that the location's official designation is The Cave of Evil, as articulated by project lead Haden Blackman and executive producer Julio Torres.
The gnarltree situated at the cave's entrance is recognized as The Magic Tree, a reference to the corresponding soundtrack cue.