First, gather up as much thermal energy as possible. On your way up the mountain make sure to destroy all of the Akrid hives. Get the rocket launcher on the metal slab jutting out of the mountain. You can also grab the large VS laser if you want a back up.
Next, climb to the top of the mountain but do not go into the cave. Stand at the top and wait for the moth to fly over you. Aim at the orange weak spots then shoot the tail part with your rocket launcher about two times. After the tail falls off do the same to the wings. A few more weak spots should appear near the top of his head. These are easier to hit with a charged laser shot. When the moth crashes into the side of the mountain the achievement will not appear. However you will bet it after you complete the mission.
Defeating the final Boss:
When the battle first starts, notice the VS will fly around, doing various little spinning attacks. Fly towards him. While doing this, do a horizontal slash). This takes a rather sufficient amount of health from the Boss. Upon doing this occasionally you can also score a second hit, but be cautious of the homing missiles. The Boss will dart around shooting little lasers at you. This is easily avoidable; simply follow in his direction to miss the attack totally. Be aware, when the boss reaches around 30% health it will call up two laser weapons. These will do massive damage if they hit you.
One is horizontal, and the other is vertical. Notice when he gets ready for this attack that he will throw his arms forward. This is your cue to get as far back as possible. The range on the lasers are fairly weak. When he is done, he will stand still for a brief moment and shoot missiles from his shoulders. Usually this is your cue to go in; the choice is yours to do so.
The Boss does not have much of a pattern. About nine well placed slashes are required to defeat the Boss.
Crossing The Plains: Defeating the giant worm:
Gather as much thermal energy as possible before you fight the worm. To get more thermal energy, destroy the surrounding heat tankards and activate the outpost. If you need more thermal energy, just kill the surrounding flying Akrid and their spawn points. Get a sled VS and attach either a rocket launcher or gatling gun (recommended). Ride it just to the entrance of the
Snow Plain. If you ride it any further the worm will knock you off and destroy the VS. Once you get off the sled VS, take off the weapon you brought with you.
The gatling gun is recommended because if you miss you can adjust your aim and keep shooting him unlike the rocket launcher. Wait until he emerges from the
snow and be ready for him to either growl or charge at you. If he charges and hits you, you are dead. You can either roll to the left or right. After the roll aim at his sides and you will see several weak points. Shoot at them until they explode and reveal a reddish boil. Continue to do this until they are all gone then switch sides. Once he is hurt enough he may start shooting flaming balls that explode from his backside. Be ready to evade them. Once again you will see more weak points. Do the same thing as done with his head side and he will eventually die. When he dies he will leave behind a large deposit of thermal energy. The worm will re-appear no matter how many times you kill it.
Thermal Energy Deposit: Defeating the giant worm:
When the worm comes out of its hole, shoot its tentacle-like arms. At the end of each arm should be claw-like hands. Shoot the claws.
If done correctly they should start turning red. Keep firing at them and they will snap off. When it snaps, the worm will go back in its hole. Run inside after it, but stop at the edge or you will fall in the lava. Look around to find the body of the beast.
Look closely and you will see a big eyeball-like thing wiggling around. Shoot it until goes in, then the arm that snapped will regenerate and come back out.
Shoot the arm and when it snaps, go back in and shoot it again. When the arm stops coming out go for the other arm and repeat this process.
Note: If you have a rocket launcher, use that and the battle will be a lot faster.
If you are taking heavy fire and would like to replenish your health (if you have the thermal energy) hop into the nearest VS. While it is doing the startup animation, you will be invincible for about five seconds.
Getting rid of pursuers:
If you have alot of Akrid or other things after you while riding the sled VS do a boost jump. While riding around you can also jump snow piles and get air.
Charge it up. When you get close to whatever you want to hit, just release it for a hit. This is easier than pressing it at the spur of the moment, because it sometimes misses.