Sometimes when I go to a room, these weird white mushrooms appear. But they always disappear before I can kill them. What am I supposed to do?

 

If I remember correctly, I can't remember if it's the white or black ones, but they do certain actions, and based on the action they do, u have to use a certain type of magic on them, if u fulfill everything they need, u get rewarded.

You cast a spell that corresponds to their movement/expression. example: Shivering = Cast Fire

What are you doing hatok? You're playing it again right?

 

You have to use a spell according to their position.

 

Here's a list:

 

Shivering: Fire

Waving it's hands like it's begging: Blizzard

Dark light on top of it: Thunder

Laying on the ground: Cure

Floating: Gravity

Spinning: Aero

Doesn't move: Stop

 

There are worlds where certain movements have a better chance of appearing:

 

Wonderland: Fire, Blizzard, Thunder

Deep Jungle: Cure

Agrabah: Gravity

Atlantica: Stop

Halloween Town: Aero

 

If you hit them with the according spell 3 times, you'll get a Spell Art.

For example: You hit the mushroom 3 times with the Fire Spell (If he shivers 3 times of course), you'll receive a Fire Arts, and if you're lucky, a Mystery Goo.

 

Once you got all Spell Arts, you can go to Merlin, and he'll give you Goofy's best shield so far: the Dream Shield, which increases Goofy's MP by 2.

Cast the spells that corresponds to there actions as stated above by another poster.