Collectible and ready to use

Cards are a strong piece of the gearing process in vanilla RO, and it isn't different in Luna Obscura.

The Key differences are:

Cards in Luna Obscura have a very reasonable drop rate. averaging 1 to 3% with bosses having up to 5% drop rates. This is because for such a customizable system, it being acessible and reward experimentation is important.
Cards can be removed at any time from the "Unslot" button on the equipment window. This has no cost and can be done anytime in a safe zone.
Cards come in multiple variations and versions.

Every card in Luna Obscura also has it's own art design. There are also special versions of certain cards with alternate art (and effects).

Card Types

They are not meant to be a mix of useless and ultra-rare pieces, but one extra customization layer on your character progression.

Cards come in a few varieties, described more in-depth in the proper page, but they can be divided in 5 types:

Monster Cards: Obtained by killing monsters, usually with 3% drop rate.
Area Cards: Obtained by completing area quests or as very rare drops. They have alternate, thematic version of cards from the area and a special art.
Foil Cards: Ultra rare cards with alternate art and effects compared to the monster cards. They have varied conditions to be obtained.
Boss Cards: Always equipped on the Badge, they have unique effects not found on other cards. They average a 5% drop rate.
Arcana Cards: They also have their own subtypes in Regular, Reversed and Occult, but are limited to Stigmatas.

Monster Cards

Different types of Cards can be equipped in different slots, and have different effects. The main parts of this division are Monster Cards and Arcana Cards.