Metroid Prime/Impact Crater

Crater Entry Point
When you arrive, there is a save station next to you so use it (this is the last one available in the game, and the only one in the crater).

Go though the door, you'll soon discover that this place isn't blue like you might expect, but orange. Orange Phazon deals twice as much damage as blue Phazon and cannot be scanned.

Crater Tunnel A
Lumigeks, Phazon-consuming lizards, will swarm toward you. Use the same tactics as with the scarabs and parasites. Jump across the Phazon and head through the door.

Phazon Core
A large room with an 'island' surrounded by Phazon. A tower-like structure connects the bottom to the top, and you must climb it. The Phazon also continuously produces a new type of Metroid: the Fission Metroid. This metroid splits in half when damaged a certain amount. The color that the smaller "half metroids" have tells its weakness. As with other enemies, yellow corresponds with the Power Beam, Red with the Plasma Beam, etc. You must use your expert platforming skills to navigate from one floating platform to another. One wrong move will land you in a large pit of Phazon. Half-way up you will find a door that leads to the Crater Missile Station.

Use the station to get a break from the extremely persistent Metroids. You're gonna need all the missiles you can get for the upcoming fight, so stock up. Head back into the Core and continue up the platforms and through the door.

Crater Tunnel B
A straight tunnel. Use the Spider Ball tracks to avoid the Phazon. Behind the door lies the fight that will determine the fate of Tallon IV.

Phazon Infusion Chamber
As the door locks behind her, Samus sees what looks like a humongous head hanging from the wall. It soon unfolds into the arachnid-ish Metroid Prime, the source of Phazon. After staring down Samus a few seconds, it breaks down the wall and makes off to a more suitable fighting area. Samus runs after it and jumps down to the fight.

Metroid Prime
The gigantic Prime can be very difficult to take down. The veins on it's carapace will change color, corresponding with which beam it's vulnerable to (similar to the Fission Metroids). However, each color gives it a powerful corresponding elemental beam attack. The yellow beam will knock out your Arm Cannon, the purple beam will cause severe static to your visor, the blue beam will freeze you, and the red beam deals more damage than the rest (also lighting Samus on fire).

Other than these, the attacks it will do regardless of color are:
 * 1) Biting
 * 2) Slashing
 * 3) Charging: Prime will sometimes attempt to trample you, so Morph Ball into the nearby ditches to avoid it.
 * 4) Releasing homing orbs towards you and freezing the ground in a straight line towards you.
 * 5) Sometimes, it will grab you with a grapple-like beam and drag you towards it. When it does, immediately turn into Morph Ball and roll in the opposite direction until it lets you go.

Throughout the battle, Prime will flee deeper into the tunnels as it takes damage. Upon defeat it falls down a large shaft, but the kill is not yet confirmed.

Essence of Metroid Prime
Samus jumps down the shaft and finds a large, circular room with blue Phazon about. Opposite of her lies the broken body of Prime, however the battle is not finished yet. A blue, transparent and octopus-looking entity floats out of the shell and attacks. All weapons are now deemed useless but one. That weapon is the previously unusable Phazon Beam! But you have no ammo! To use it you must wait for Prime to produce an ultra Phazon pool, but producing Metroids as well. Upon stepping in the pool, your visor blurs a bit and it says "HYPER MODE". Unleash as much damage to Prime as quickly as you can! The pool doesn't last forever! Now, this doesn't mean Prime is defenceless! It has many powerful moves:
 * 1) Whip. Hit you with tentacles. Back off.
 * 2) Camo. Disappears. Use Thermal/X-Ray(one works one time, maybe again) to see it!
 * 3) Summon Metroids and a Phazon Pool. Depends on heath. Summons regular, Hunter, or Fission.
 * 4) Spin Whip. "Back Off!" move. You SHOULD back off.
 * 5) Ram. Self Explanatory. Side strafe to dodge. Rarely used.

Keep fighting hard and you should win. If you lose, too bad! The end movie depends on items collected. See Metroid Prime/Endings for a description of all three.