Face down
Two cards (Illusionary Mask and Ixidron) and the morph and manifest abilities allow spells and permanents to be face down. If a permanent is turned face down by a spell or ability, it becomes a 2/2 face-down creature with no text, no name, no subtypes, no expansion symbol, and no mana cost. A card that enters the battlefield face down also has these characteristics.
Turning a face-down creature face up doesn't use the stack and can't be responded to. If the face-down creature has any counters on it, those remain on the face-up creature. It's not a new creature, and it doesn't enter the battlefield just by turning face up. Any Auras or Equipment attached to the manifested creature remain attached to it after it turns face up. There are three enchantments in Fate Reforged that manifest a card and then become an Aura attached to it.