In this rule

Historical Rules · 27 February 2026

Rule 702.145e

Official source text from the 27 February 2026 Rules release

Permalink

Nightbound is found on the back faces of some double-faced cards and represents two static abilities. “Nightbound” means “As it becomes day, if this permanent is back face up, transform it” and “This permanent can’t transform except due to its nightbound ability.”

Find this number in the current Rules