Activating the spell card is just 22 D.
then your character gets a magic circle.(that's just for display)
and to use the card, its 236 D.
In story mode, the other characters have a special spell card that is not usable.
Or its an upgraded version of a playable spell card.
Patchouli is really easy to play, because all you have to do is attack the enemy from afar.
Notice the red portion on Marisa's hitpoints bar? When you beat her up to that portion, she activates a spell card. Yup. She'll use it until you kill her. If her hitpoints bar is all red, that means she'll immediately activate a spell card and won't stop until you knock her down.
When advancing stages, you'll need to kill the enemy more than twice.(of course in games it always gets harder and harder
)
So good luck.