How to Beat No. 6 of Mushroom XIII in Kingdom Hearts II

Preparing Your Character

Locate Mushroom no. 6. Before you start, you have to know where your target is. Mushroom no. 6 is located at the Atrium in Olympus Coliseum, the place where you fought Demyx's water clones. To get there, warp to the Lock and exit through the only door in the area.

Place ethers on all your item slots. You'll need ethers because you'll be spamming Thundaga a lot.

Equip Ultima Weapon on your normal form. Ultima's unique ability MP Hastega will be very useful for this challenge since you'll need to regenerate your MP faster.

Equip Photon Debugger on your Final form. It's Thunder Boost ability will help you deal more damage quicker and will help you take out mushrooms faster.

Place the Thundaga ability on your shortcuts. Thundaga will be your main killing skill since it's long-ranged and has a wide area of effect.

Beating Mushroom no. 6

Drive into Final form then press ∆ to start the challenge.

Hit the first mushroom with a normal attack. It will spawn more mushrooms.

Lock onto the mushrooms as they appear and cast Thundaga. This will wipe them out quickly, but depending on how far you're standing from them, you might not be able to attack them, so make sure you're in the middle of the area.

Use an ether when your MP runs low. Make sure you use it when it's low, not when it's already empty. This will help you lessen the time needed to charge your MP since ethers can't heal Sora's MP entirely. Use ethers after killing the mushrooms, not after they've spawned. This will help lessen unnecessary waiting time.

Continue casting Thundaga until the challenge is over. Using the Thundaga method will give you at least 39 seconds on the counter.