Kingdom Hearts
Infinite magic
This method requires that you have the summons spell Bambi, which you can get in 100 Acre Woods. The abilities of Treasure Magnet and Jackpot are also very good to have. Unlimited magic is actually quite intuitive, though not necessarily obvious to all players: Summon Bambi, and have the Treasure Magnet and Jackpot abilities on. This enables the quick collection of, and increases the number of Magic Bubbles Bambi drops, respectively. You will get magic back at an incredible rate. This can be used throughout a battle, or simply to refill your magic at the end of a battle without the need for Ethers. It is best to summon Bambi and fill up your magic bar just before killing the last creature you are fighting. Also, unlimited magic also means unlimited health when coupled with the Cure spell. Of course, Bambi will not appear everywhere, such as the Coliseum, where this method would be extremely useful.
Life
Get 200 Mushrooms in the first town. You can sell them at Trevers Town to get extra life.
Oblivion
After defeating Riku for the last time in Hollow Bastion, return once you regain control of the Gummi ship. Go to where you fought Riku and go up the stairs to the wall opposite the Keyhole entrance. There will be a chest there containing Oblivion, one of Sora's strongest weapons.
Ultima Weapon
The Ultima Weapon is the best Key in the game. Synthesize all the items. After you complete the 25th item, the Ultima Weapon will appear. This is Sora's best weapon. It requires five Lucid Gems, five Power Gems, five Thunder Gems, three Mystery Goos, and three Gales. It is very powerful and adds 2 MP.
Defeating Ice Titan
Seal the Keyhole at Hollow Bastion. Complete the Hades Cup and a new option will appear, for the Gold Cup. Here, you will fight an old enemy from Hercules. He is too tall to hit. Stand on the bleachers and reflect his ice attacks back at him. Being level 63 is recommended.
Defeating Kurt Zisa
Seal the Keyhole at Hollow Bastion. Then, in Agrabah, go to Aladdin's house and talk to Carpet (he is jumping around frantically). He will bring you to Kurt Zisa. Hit his hands until you break the orbs, then hit his head. When he floats in a bubble, you will need to use magic, such as Mushu. Being level 65 is recommended.
Take Aladdin and Goofy with you. Aladdin will be useful for attacking and Goofy for healing. Equip your characters (including Sora) with nothing else except Potions and Hi-Potions. Also, equip Sora with his rolling technique. Immediately when the fight begins and your small attack screen appears, go to "Magic" and summon Tinker Bell. She will heal your characters and will prevent Sora's death once. Start attacking his hands, one combo, and move away from Kurt Zisa with your rolling technique. Keep repeating this until you destroy both of his hands and he falls. Then attack his head. After he stands up again, he will allow you use magic. The only way to inflict damage is by casting spells on him. Blizaga works well. Note: When he raises his hand, stop. You will have a whirlwind around you. Look well and roll out of it. Also, when he starts to throw fire, run after him and keep casting spells on him. When he falls for the second time, attack his head. You will get him quite angry. Keep attacking him as done the first time, but with caution. He is faster and has a new move. He will start to spin around. When he spins horizontally, jump and glide until he passes under you. When he spins vertically, run and roll. He usually always hits you when he rolls horizontally -- keep your potions ready. When he falls and you hit his head again, he will stand up again. Cast spells on him as done before, but you now has yet another new move. However, it is quite easy to evade. You will see the sand moving -- keep rolling around and do not stop or the magic balls will hit you until the largest magic ball has gotten out of the sand. Roll around the outer part of the arena. He will fall again. Once again, keep casting spells on him. If these four take down attempts are not enough to defeat him, repeat the steps.
Defeating Sephiroth
After sealing the Keyhole at Hollow Bastion, a mysterious battle appears in Phil's list of options. This battle is called the Platinum Match, and you must go one on one with the toughest Boss in the game to win.
Sephiroth is very difficult. You need to complete the Hercules Cup or lock the Hollow Bastion Keyhole. He is very fast and does a lot of damage. When you hit him, it appears that you are doing no damage, but you are. You need to hit him about twenty times to get his life bar to start moving, then he will do a finishing move where he disappears. He will appear behind and probably kill you. Being at a very high level (about 85) and having the Ultima Weapon is recommended.
When you start talking life, he will do Heartless Angel, which lowers your health to 1 and MP to 0. After his life goes down a bar or two, he will run at you and do a deadly combo. Try to stay away -- gliding will not help. When he has one bar remaining, he will glow blue and make blue orbs appear around you. He will then make a group of large blue rocks appear. They will move around the battle field in a circle, then cast Meteor. If you are lucky and remain alive after this, continue attacking him. He will do it again. When he is almost dead, he will run around and not stop, becoming very difficult to hit. Hit him a few times to winthe battle. You will get about 60,000 experience points.
The Ultima Weapon or the Oblivion (found in Hallow Bastion just on the upper level behind you after you defeat Ansem/Riku) and being at level 80 to 85 is recommended. Study his moves and attack pattern. He usually five slashes then casts Halo (three huge fire pillars). Strike him after he casts Halo, or strike him when he jumps at you and attempts a slice attack. After giving him four slashes, he fades away and appears behind you, doing a surprise slice. However, this does not happen very fast and gives you about five seconds to jump away. The "invisible" life gauge he has will wear off and he will begin to lose health. Keep repeating this until the orange appears. He will fade away and start to taunt you. He will run at you but will fade again. Use the lock function on him as soon as he fades. You will lock on him, and when you have him on sight, speed glide or run at him then slice at him to interrupt Sin Harvest move. This move is similar to Heartless Angel, but it takes away your MP as well. If you are too slow, have some Hi Potions or Elixirs ready. In his second stage, you will have be quick and use the lock on continuously. Once he fades, you will have to lock on again. Dodge all his slices, especially his special. Whenever you get hit, keep casting Curaga on yourself. Repeat the same strategy until his life gauge is yellow and green. He will call out meteors. Try to dodge them. They will thump down and spin for a bit before exploding. He will throw a huge energy ball at you which takes off quite a bit of health. Cast Curaga on yourself to help. He will turn blue, be stronger, and slash repeatedly. Having MP Rage and MP Haste will help. Slice at him when you have the chance to defeat him.
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