Rules glossary
↑ Parent rule: 731.2 As the second part of the untap step, the game checks the pr…
731.2b If it’s night, and previous turn’s active player cast two or more spells during the previous turn, it becomes day. Multiplayer games using the shared team turns option (see rule 805) use a modified rule: if it’s night and any player from the previous turn’s active team cast two or more spells during that turn, it becomes day.
No sub-rules.