Historical Rules · 18 February 2022
Rule 702.145b
Official source text from the 18 February 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, this permanent 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 724, “Day and Night.”