Historical Rules · 17 November 2023
Rule 702.145b
Official source text from the 17 November 2023 Rules release
Daybound is found on the front faces of some transforming double-faced cards and represents three static abilities. “Daybound” means “If it is night and this permanent is represented by a transforming double-faced card, it enters the battlefield transformed,” “As it becomes night, if this permanent is front face up, transform it,” and “This permanent can’t transform except due to its daybound ability.” See rule 726, “Day and Night.”