Historical Rules · 13 October 2023
Rule 502.2
Official source text from the 13 October 2023 Rules release
Second, if it’s day and the previous turn’s active player didn’t cast any spells during that turn, it becomes night. If it’s night and the previous turn’s active player cast two or more spells during that turn, it becomes day. If it’s neither day nor night, this check doesn’t happen and it remains neither. This turn-based action doesn’t use the stack. See rule 726, “Day and Night.”