Mustafar is a small volcanic planet in the Outer Rim, its surface dominated by rivers and seas of lava flowing between black obsidian mountains. The planet's unstable orbit between two gas giants creates extreme gravitational forces that tear at its crust, resulting in constant volcanic activity. Despite the inhospitable conditions, the native Mustafarians evolved to survive here, mining the valuable minerals created by the unique geological conditions. Mustafar later became infamous as a secret Separatist stronghold during the Clone Wars and, more significantly, as the site where Anakin Skywalker completed his fall to the dark side in his duel with Obi-Wan Kenobi. The planet later housed Darth Vader's personal fortress, Fortress Vader, becoming a nexus of dark side energy and a symbol of the consuming fires of hatred and power.