Historical Rules · 10 June 2022
Rule 702.145b
Official source text from the 10 June 2022 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 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 be transformed except by its daybound ability.” See rule 725, “Day and Night.”