Things You'll Need
Instructions
Locate your Duel Spirit's card and add it to your deck. It is important that the card is with you when you fight or the spirit will not get any experience points.
Begin a duel with an opponent. This can be any opponent you face for regular experience points at any point in the game.
Summon your Duel Spirit by using its card during the duel. For example, if you have an "Oscillo Hero #2" card, you need to actively use it in battle in order for it to grow and strengthen.
Defeat your opponent. If you do not do this, you will not receive experience points for your spirit.