Playtest

A playtest is the process by which individual cards, as in card design, or sets of cards, as in decks, are played to test the card or cards for design issues to establish a desired quality.

In the context of deck playtesting, this often involves in testing a given deck against popular decks in a format's metagame and accordingly modifying the decklist, its main deck and its sideboard, to better deal with those decks.