Rules glossary
↑ Parent rule: 701.40 Manifest
701.40a To manifest a card, turn it face down. It becomes a 2/2 face-down creature card with no text, no name, no subtypes, and no mana cost. Put that card onto the battlefield face down. That permanent is a manifested permanent for as long as it remains face down. The effect defining its characteristics works while the card is face down and ends when it’s turned face up.
No sub-rules.