Metroid Prime Lair

From Wikitroid, the Metroid wiki

The Metroid Prime Lair is the last room in the Impact Crater and is the last room in Metroid Prime. It is where you face the true form of the Metroid Prime. It is the only place in which you can use the Phazon Beam as a result. In the room there is the empty shell of the Metroid Prime in some solid blue Phazon.