Deck building games start every player with the same small, fairly weak deck of cards. As you play, you spend resources to buy stronger cards that get shuffled into your own deck, so the choices you make slowly turn a pile of basics into a finely tuned machine. Because you draw a fresh hand from a shuffled deck each turn, you are always balancing what you add: a flashy expensive card is useless if it clogs a deck full of clutter. The fun is watching your deck transform and firing off a perfectly chained turn you built yourself.