Dagobah was one of the purest planets in the galaxy, alive with the Force thanks to its abundant life. One cave in the planet’s swamps roiled with the dark side. During the Clone Wars, the spirit of Qui-Gon Jinn led Yoda to this cave, where Yoda had a vision of Darth Sidious’s triumph over the Jedi. Years later, Luke Skywalker faced his own test in the cave, fighting a saber duel with a spectral Darth Vader whose helmet concealed Luke’s own face.