aero learned after defeating Opposite Armor in Traverse Town. These are necessary bosses to advance the story and cannot be missed.
Aerora learned by activating the Yellow Trinity in Hold on Captain Hook’s ship in Neverland.
Aeroga studied after rescuing 99 puppies. Jiminy Journal has a great checklist to help you with this!


What Are Aero Spells & What Do They Do?
Aero Spells create a whirlwind around characters that reduces the damage they take by half.
Second and third level spells get a little extra besides damage reduction:
Aerora deals damage to enemies who touch Sora, while Aeroga deals damage to enemies and can deflect small projectiles, such as low-level magic.
All Aero versions cost 2 MP per cast.
The formula for how long the Aero lasts is:
18 Seconds + [Sora’s Max MP]
For example, if Sora has 9 MP max, then you’re looking at Aero which is 27 seconds long.
Tip: the optional Ice Titan boss is the only place where you don’t wanted to cast Aero, as doing so would increase his attack to an almost implausible level.


Is Aero Worth Using?
Yes!
Aero is one of the few spells in the game that feels overpowered. It’s cheap to throw and cuts the damage taken in half.
On Normal and Standard (Final Mixed) difficulty this helps, but on Proud it’s only about required.
Proud Mode doubles all damage Sora takes by the wayso Aero makes the playing field back to normal.
Furthermore, Pink Agaricus, the new heartless introduced in Final Mix, is many easier to effectively defeat and farm with Aeroga.
So yes! Use Aero with reckless abandon.
You get Aero as part of the story and it’s well worth your time looking for upgrades as soon as possible.