Cards

There are various types of cards in Legend Online:
 * 1) Character Cards
 * 2) Monster Cards
 * 3) Goddess Cards
 * 4) Legendary Cards

Each card can has a certain max level. Cards are levelled at the Altar by sacrificing either another card into it or an XP Fruit (Blood Fruit/Spirit Fruit). XP Fruits can be obtained from Nightmare Meadow in the Activity Tab of Campaign.

More about Activity Tab here.