This will probably contain spoilers, so read at your own digression.
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GENERAL CONCEPTS:
Levels
Card levels, ranging from 1-6, are a fixed measurement of a card's rarity, power, and potential. (Typically, the higher the card level the rarer it will be).
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Ranks
Card ranks, ranging from 1 (base rank) to 6 (aura rank), represent the general progression of a card's power. Through repeated use and experience, a card can evolve overtime, gaining a number of stars (✧) in correlation to its current rank/power level. (Some cards can rank up faster than others. It typically varies depending on the user).
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Class
Card Class pretty much determines the way in which a card can be used. They are split into 3 main categories:
Combat - A card with offensive capability.
Defense - A card capable of protecting the user or others from attacks in any way.
Utility - This class describes cards that are not primarily used to attack or defend. It includes mobility cards, cards that can buff, etc.
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Type (SPOILER WARNING!)
Along with a class, which determines how a card is used, there are 'card types' that constitute the way in which cards execute their abilities. There many different card types (some that may not be introduced until later volumes):
Birth Card/Soul Card - The card that you are born with or bestowed. Birth cards are essentially a source of life for card holders; if the card is no longer bound to you, you will die, and if you die in any way, the card will be destroyed. If you are killed by a card holder, however, the card has a chance to select them as its new owner. You can also perform what's known as a SoulSacrifice, to bestow someone your card in exchange for your own life. It is possible to possess more than one Birthcard, and each one owned by an individual counts as an extra life. But if you were to die with more than one in your possession, all your collected card would be Recycled meaning they would be transported into random dungeons as reward. (Birthcards do not possess levels as they are innate, but they can still rank up).
Bestowed Cards - Bestowed cards function the exact same way as birth cards, however, their manifestos are pre-determined by the will of their original owner, and therefore cannot be written by the current owner.
Manifest - Cards that allow the users to wield their stored abilities themselves. Some may require certain actions (Conditional Manifest) and other may not (Unconditional Manifest).
Summon - Cards that can summon loyal beasts/sentient devices.
Tool - These cards can project their own stored ability instead of allowing the wielder to use it. They are commonly projectiles that shoot out of the card instead.
Trap Cards - Cards that can be hidden around the user's environment within a certain range (Vision Field). Once willed by the user, or triggered by the enemy, the ability will activate automatically.
X-Tool/Tool Ex - Incredibly rare cards that contain special weapons believed to originate from a dimension within the card itself (the Void). They are made of an unknown, indestructible, unobtainable and irreplicable resource that most people refer to as Void Energy. These Void Weapons possess immense power, requiring a significant amount Vision energy and stamina to wield. The weapons cannot be wielded by anyone other than the user.
Attribute Cards (Potential Spoiler) - Attributes or 'Path Attributes' can be considered stat bonuses. When owned by the user, it boosts a range of their physical capabilities depending on the attribute type: Chivalry (Boosts Physical Endurance), Frailty (Boosts Range of sight, and Accuracy from long range), Agility (Enhances Speed and Reflexes), Mighty (Boosts Physical Strength), and Egoity (Boosts Stamina and Dexterity). All cards can have an attribute attached to it, but those kinds of cards are harder to find. You can also own more than one attribute card, and any type of attribute you desire.
Empty Cards (Potential Spoiler) - Cards that are empty can have anything stored inside them to transform the card into anything the user desires. You can experiment with different substances and elements to form an ability that incorporates those things (e.g. adding fire and water to create a smokescreen ability). The higher the empty card level, the stronger the created ability will become. You can store defeated beasts/beast cores inside empty cards as well, which will turn them into summons. However the maxim level of the beast you can capture must align to the level of the empty card. For instance, a level 2 empty card can only capture beasts up to level 2, meaning level 1 and 2.
God Cards (Potential Spoiler) - Powerful cards contain the will of deceased monarchs. They are usually level 6 cards, which require certain sacrifices and rituals to obtain.
Longevity (Potential Spoiler) - Incredibly rare cards that grant the wielder a permanent passive effect as long as it remains bound to them.
Tainted (Potential Spoiler) - Cards that are wielded by anomalies (objects, the living dead, etc.). These cards have mutated due to the unconventional state of the user, becoming unreadable and increasingly destructive. They also can never rank up from their given rank.
(It is possible to be born with any of these listed card types, but some are much rarer than others).
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Mount
Mount cards are generally vehicles that can be summoned by cards. There are several types of mounts that cater to certain environments:
Sand Surfers: Vehicles made for traversing deserts. They typically hover slightly above the sand and have quiet motors.
Land Rollers: Vehicles built to travel across any earth terrain. They typically possess wheels and loud motors.
Sky Cruiser: Vehicles that can fly. They possess large propellors and wings, and are much rarer to find.
Mud Sailor: Used for traversing murky terrain.
Marine Voyager: Big ships for traversing the sea.
Marine Drifter: Smaller boats that occupy less people.
Deep Voyager: Large submarines.
Deep Drifter: Smaller submarines.
(All mounts require artificial Vision energy, typically in the form of insertable capsules, for fuel and power. Some summoned beasts can also be used as mounts. Although some versions are more practical than others, these cards do not possess ranks or levels).
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Manifesto
A Manifesto is a conditional rule that a user must create and set on a card once it reaches a certain rank, granting flexibility and increasing its power. At it's highest rank, it is possible to have three manifestos on a single card, however, most cards will only possess two at max. (Only Birth cards can have Manifestos. It is also possible to sacrifice a Manifesto to gain an attribute on the card instead).
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CCU
A standard abbreviation for Card Containment Unit. It is a necessary device for Collectors as it allows them to not only store their cards, but summon them as well since it's required to create a Vision Field. CCU's can also come in a variety of different models, which are typically found in Black Market districts. (Better models can allow you to see more stats within an person's card when using Clairvoyance).