Deck building/Pool building refers to a collection of related mechanisms. Players have a personal pool, or collection, of cards or tokens, that provide different actions and/or resources. A subset of those cards/tokens are randomly drawn each turn. An important aspect of the game lies in managing the contents of that pool by adding and removing cards and tokens over the course of the gameplay, often through the very actions provided by the cards/tokens themselves. Over time, players build decks/pools that are more and more specialized and effective towards some purpose(s), typically including claiming victory objectives. Deck/pool-building may be the central mechanism of a game, or it may be one part of a larger system.