When The Grand Calcutron enters, each player's hand becomes a program (an ordered row of revealed cards).
Players can
playTo play a land means to put it onto the battlefield from the zone it’s in (usually the hand). A player may play a land if they have priority, it’s the main phase of their turn, the stack is empty, and they haven’t played a land this turn. Playing a land is a special action (see rule 116), so it doesn’t use the stack; it simply happens. Putting a land onto the battlefield as the result of a spell or ability isn’t the same as playing a land. See rule 305, “Lands.”
To play a card means to play that card as a land or to cast that card as a spell, whichever is appropriate.
Some effects instruct a player to “play” with a certain aspect of the game changed, such as “Play with the top card of your library revealed.” “Play” in this sense means to play the Magic game.
Previously, the action of casting a spell, or casting a card as a spell, was referred to on cards as “playing” that spell or that card. Cards that were printed with that text have received errata in the Oracle card reference so they now refer to “casting” that spell or that card.
Previously, the action of using an activated ability was referred to on cards as “playing” that ability. Cards that were printed with that text have received errata in the Oracle card reference so they now refer to “activating” that ability. (CR 701.18) only the first card of their program.
If a card would be put into a player's hand from anywhere, that player reveals it and places it anywhere within their program instead.
At the beginning of each player's end step, if that player's program has fewer than five cards, they draw cards equal to the difference.
The Grand Calcutron can be your
commanderA designated card for a Commander deck, governed by the command-zone, color-identity, and Commander rules. (CR 903).