If it is day, and the active player of the previous turn cast no spells during their turn, it becomes night.
Graveyard Trespasser // Graveyard Glutton
Day and night are designations that the game itself can have. The game starts as neither. Once the game becomes day (or less commonly, night), the game will be exactly one of them—day or night—going back and forth for the rest of the game.
Before a player untaps their permanents during the untap step, the game checks to see if the day/night designation should change.
Magic: The Gathering · ™ & © Wizards of the Coast · Illus. Chris Rallis
Card data via Scryfall. Rarix is fan-made; not endorsed by the rights holders.
