Comprehensive Rules
702.168b
To cast a card using its disguise ability, turn the card face down and announce that you are using a disguise ability. It becomes a 2/2 face-down creature card with ward 
, no name, no subtypes, and no mana cost. Any effects or prohibitions that would apply to casting a card with these characteristics (and not the face-up cardâs characteristics) are applied to casting this card. These values are the copiable values of that objectâs characteristics. (See rule 613, âInteraction of Continuous Effects,â and rule 707, âCopying Objects.â) Put it onto the stack (as a face-down spell with the same characteristics), and pay 
rather than pay its mana cost. This follows the rules for paying alternative costs. You can use a disguise ability to cast a card from any zone from which you could normally cast it. When the spell resolves, it enters the battlefield with the same characteristics the spell had. The disguise effect applies to the face-down object wherever it is, and it ends when the permanent is turned face up.
, no name, no subtypes, and no mana cost. Any effects or prohibitions that would apply to casting a card with these characteristics (and not the face-up cardâs characteristics) are applied to casting this card. These values are the copiable values of that objectâs characteristics. (See rule 613, âInteraction of Continuous Effects,â and rule 707, âCopying Objects.â) Put it onto the stack (as a face-down spell with the same characteristics), and pay rather than pay its mana cost. This follows the rules for paying alternative costs. You can use a disguise ability to cast a card from any zone from which you could normally cast it. When the spell resolves, it enters the battlefield with the same characteristics the spell had. The disguise effect applies to the face-down object wherever it is, and it ends when the permanent is turned face up.