If a card is played for its special event, it is removed from the game, so the pack of available cards gradually diminishes as the game progresses. A player may also automatically make a single activation without the need to play a card, which may be necessary if s/he has played most of the cards out of their hand (e.g. through playing too many combat cards), or if s/he is trying to retain a key card in their hand for use on a future turn. Cards with key events are also likely to have high values for Operations and Replacement points, requiring a player to make critical choices each turn in managing their hand of cards.