Rules glossary
↑ Parent rule: 731.2 As the second part of the untap step, the game checks the pr…
731.2a If it’s day and the previous turn’s active player didn’t cast any spells during that turn, it becomes night. Multiplayer games using the shared team turns option (see rule 805) use a modified rule: if it’s day and no player from the previous turn’s active team cast a spell during that turn, it becomes night.
No sub-rules.