Cards are arranged into decks for quests and battles. You can have up to 10 cards in a normal deck and 5 cards in a raid deck.
Before the battle starts, one deck is automatically chosen from your deck list based on priority. You can adjust the priority of a deck by up to three; the higher number is chosen first.
There will always be a recommended stat deck that may be chosen if the player does not wish to build their own deck.
You can choose any Eidolon Card to be the leader of the deck. The leader's stats are multiplied by 1.5 in battles and boss encounters.
Sub Leader Edit
You can set any Eidolon Card to be the sub leader of the deck. The sub leader's INT stat is multiplied by 1.5 in Battles.