In Lost Ark, there is a card system—not one that you use in a minigame, but more of a collectible. You can buy card packs from the in-game store, with a chance to get any rarity of cards. Books are tied to the card system in Lost Ark.
Books are essentially cards, as well. There are two types of cards: one that you can equip for a bonus if more than one of the same type is equipped, and a collectible card that—once you have the entire set of(the set is called a book)—gives you permanent stat bonuses.
There are over 692 cards to collect, with 173 sets in total. That is 173 permanent stat bonuses just for collecting cards. Yes, these cards are mostly purchased from the in-game store, but you also get some for completing quests.
This may be a translation error and possibly will be fixed in the full-fledged release of Lost Ark in 2022.
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