OK, I'll use the Heartless card, now

You take out the Heartless card and show it to the door. The door then opens and as you walk through the door, again you are welcomed by a blinding white light. As the light disappears, you face a group of Heartless. You battle them and defeat them all, one by one. After finally leveling up again after those Heartless battles, you suddenly are back in the same wood, just a little bit stronger than before. You know you still cannot use the story card just yet, because you have not achieved the minimum level, but at least you have become a little stronger.

I guess that means you'll have to use that Heartless card 4 more times, right? Maybe 5 to be safe?

Level Up! (+25 HP, +25 MP, +15 SP)

Stats
Level 3
HP: 150
MP: 150
SP: 130