The Main Reactor is a room in the Agon Wastes. The room connects the Sand Processing, Storage D, Ventilation Area A, by a White Hatch, and Security Station B, by a Purple Hatch. The room consists of a central room, surrounded by an upper walkway. The center room is taken up by a large number of tanks that contain large amounts of Phazon. The largest of these tanks is located in the center of the room. There are a series of tanks on one side of the room that can be navigated through using Spider Ball Tracks and the Boost Ball. Each tank has moving parts that will block the way, along with damaging Phazon on the bottom. If Samus falls to the bottom, she can leave each tank using a small hole leading back to the main room. If Samus successfully navigates the tanks, she will acquire a Missile Expansion at the end. The upper walkway has two sections. The main section has doors to the Sand Processing, Storage D, and Security Station B. Each door is separated by a gate that can be lowered by hitting a white crystal with the Dark Beam. There is an elevator connecting the levels near Storage D. There is also a large opening near the door to the Sand Processing, next to a dark purple area that is the destination of a Portal in the Dark Oasis. The Door to Ventilation Area A is located in a separate section, that can only be accessed from below using a Spider Ball Track. This section has the corpse and final testament of B-Stl. When Samus first enters the room, she sees Dark Samus absorbing energy from the central tank. When Samus enters the main room, a battle will start. When Dark Samus has been destroyed, the elevator will be activated.