When a card is turned face down through the manifest mechanic (or morph), it becomes a 2/2 face-down creature with no name, no mana cost, no creature types, no subtypes, and no abilities. It is colorless by default because having no mana cost means no color identity is applied. This is defined in CR 707.2.
CR 707.2 states that a face-down permanent has no characteristics other than those granted by the face-down status itself — specifically, it is a 2/2 colorless creature with no name, subtypes, supertypes, expansion symbol, rules text, or abilities. The card's printed characteristics are simply ignored while it is face down.
This means removal spells or effects that target creatures of a specific color or type (e.g., 'destroy target white creature' or 'destroy target Human') cannot legally target or affect the face-down creature based on those criteria, since it has none. A spell saying 'destroy target colorless creature' could target it, however, since it is indeed colorless.
Concrete example: You manifest a Plains (a white card) onto the battlefield face down. Your opponent casts 'Doom Blade' which reads 'Destroy target nonblack creature.' The face-down Plains is a colorless 2/2 creature — it is neither black nor any other color — so it is a legal target for Doom Blade and will be destroyed.
Once the permanent is turned face up (if it's a creature card and you pay the appropriate cost), it immediately regains all of its actual printed characteristics. CR 702.36 covers morph and CR 702.145 covers manifest specifically, both referencing CR 707 for the face-down rules.
Unofficial fan resource — not affiliated with or endorsed by Wizards of the Coast. Answers are AI-generated estimates grounded in the Comprehensive Rules and are not a substitute for an official judge. Verify anything match-critical.