Metroid Prime/Plasma Beam

Go to the Geothermal core in Magmoor Caverns. Route: At the bottom of the Root Cave is the entrance to Transport Tunnel B then proceed to Transport to Magmoor Caverns East, Transport to Tallon Overworld West, Twin Fires Tunnel, Twin Fires and North Core Tunnel. Level up the platforms in the core. Then you use the ../Spider Ball/ along the wall and enter the ice door, and there in the middle of the room is your Plasma Beam.