The curse makes it so that if you say the words "ground battle", a ground battle is all you can do.

Which is why—

Would you like some orange juice?

Put some ice in it.

I KNEW THAT WOULDN'T WORK!!

Now, now. Try to calm down.

Just leave already.

That last attempt ended in failure, but...

Yeah.

The point is to cast a curse on her words.

Whether the person realizes it or not, words are a contract.

Even the greatest magician can be bound by words. A true contract can not be broken.