702.34 - Morph
702.34a - Morph is a static ability that functions in any zone from which you could play the card it's on, and the morph effect works any time the card is face down.
"Morph <-cost->" means "You may cast this card as a 2/2 face-down creature, with no text, no name, no subtypes, no expansion symbol, and no mana cost by paying 
rather than paying its mana cost." (See Rule 707, "Face-Down Spells and Permanents.") [CompRules 2009/07/08]
702.34b - To cast a card using its morph ability, turn it face down. It becomes a 2/2 face-down creature card, with no text, no name, no subtypes, no expansion symbol, and no mana cost. Any effects or prohibitions that would apply to casting a card with these characteristics (and not the face-up card's characteristics) are applied to casting this card. These values are the copiable values of that object's characteristics. (See Rule 613, "Interaction of Continuous Effects," and Rule 706, "Copying Objects.") 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 morph to cast a card from any zone from which you could normally play it. When the spell resolves, it enters the battlefield with the same characteristics the spell had. The morph effect applies to the face-down object wherever it is, and it ends when the permanent is turned face up. [CompRules 2009/07/08]
702.34c - You can't cast a card face down if it doesn't have morph. [CompRules 2009/07/08]
702.34d - If you have priority, you may turn a face-down permanent you control face up. This is a special action; it doesn't use the stack (see Rule 114). To do this, show all players what the permanent's morph cost would be if it were face up, pay that cost, then turn the permanent face up. (If the permanent wouldn't have a morph cost if it were face up, it can't be turned face up this way.) The morph effect on it ends, and it regains its normal characteristics. Any abilities relating to the permanent entering the battlefield don't trigger when it's turned face up and don't have any effect, because the permanent has already entered the battlefield. [CompRules 2009/07/08]
702.34e - See Rule 707, "Face-Down Spells and Permanents," for more information on how to cast cards with morph. [CompRules 2009/07/08]
