Rules glossary
↑ Parent rule: 730.2 To merge an object with a permanent, place that object on to…
730.2j A face-up merged permanent that contains a double-faced component can’t be turned face down. If a spell or ability tries to turn a face-up merged permanent that contains a double-faced component face down, nothing happens and that effect doesn’t change any of its characteristics or their copiable values.
No sub-rules.