Phazon Beam

The Phazon Beam is an immensely powerful beam weapon, that first debuted in Metroid Prime. Since then it has appeared in some form in the sequels, Metroid Prime 2 and Metroid Prime 3.

In Metroid Prime
In Metroid Prime, the Phazon Beam is used against the final boss, the eponymous Metroid Prime. When the corrupted Phazon Suit comes into contact with liquid Phazon, it goes into "Hyper-Mode", supercharging Samus' Arm Cannon and allowing her to shoot a continuous stream of destructive energy. The Phazon Beam is the only weapon that can damage the second form of the Metroid Prime. Unlike the Hyper Beam, which can be fired anytime, Samus Aran must step into a small pool of pure concentrated Phazon to use the Phazon Beam, which means it can only be used when Metroid Prime creates them. Samus can only utilize the Phazon Beam as long as there is Phazon to draw from; each shot uses up Phazon in the pool, so make the most of it. The Charge Beam is incompatible with this version of the Phazon Beam; holding down the fire button will allow for a continuous beam attack.

In Metroid Prime 2: Echoes
Samus also uses a sort of Phazon Beam in this game, although it is not an actual power-up. In the final boss fight, Dark Samus occasionally fires tiny balls of Phazon that Samus must catch with the Charge Beam. When three of these Phazon balls are absorbed, Samus can fire them back at Dark Samus to hurt her (absorbing more than three does not increase the strength of the beam). Any beam will work with this, so charged Phazon versions of the Power, Dark, Light, and Annihilator Beams exist (there is no difference other than minor graphical ones, however and using the Light, Dark, or the Annihilator Beam will not waste ammo when fused with Phazon energy). Strangely, when this shot is used outside of the fight (via hacking), it can open any door (with the exception of the Seeker Missile doors, due to their unique opening mechanism), break any substance, and does extensive damage to bosses.

In Metroid Prime 3: Corruption
Near the beginning of the game, Samus can enter Hyper Mode manually using her PED Suit, and use her Phazon energy/health to power it, and fire single blasts of phazon energy. The charged version of this ha s Samus shooting out a stream of Phazon energy, dealing significant damage to nearly any enemy and using 4 units of energy per shot. This beam is called the Hyper Beam. As the charged shot is firing, the tip of the Arm Cannon spins, and the whole action looks similar to a Gatling gun firing.