At the end of Metroid Prime, the the titular creature's core essence engages in battle with Samus, and occasionally releases pools of liquefied Phazon onto the ground. As the Metroid Prime's only weakness is an overload of Phazon, Samus utilizes these Phazon pools to supercharge her Arm Cannon with the Phazon Beam. This is the only time the Phazon Beam can be used, and the pools dry up after some time or enough use. Various forms of Metroids spawn from the Phazon, summoned by Metroid Prime to distract Samus.