From the glossary of the Comprehensive Rules (July 12, 2019—Core Set 2020)
Morph
A keyword ability that lets a card be cast face down as a 2/2 creature. See rule 702.36, “Morph,” and rule 707, “Face-Down Spells and Permanents.”
From the Comprehensive Rules (July 12, 2019—Core Set 2020)
702.36. Morph
702.36a 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, and no mana cost by paying {3} rather than paying its mana cost.” (See rule 707, “Face-Down Spells and Permanents.”)
702.36b Megamorph is a variant of the morph ability. “Megamorph [cost]” means “You may cast this card as a 2/2 face-down creature with no text, no name, no subtypes, and no mana cost by paying {3} rather than paying its mana cost” and “As this permanent is turned face up, put a +1/+1 counter on it if its megamorph cost was paid to turn it face up.” A megamorph cost is a morph cost.
702.36c 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, 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 {3} rather than pay its mana cost. This follows the rules for paying alternative costs. You can use a morph ability 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.
702.36d You can’t normally cast a card face down. A morph ability allows you to do so.
702.36e Any time you have priority, you may turn a face-down permanent you control with a morph ability face up. This is a special action; it doesn’t use the stack (see rule 116). 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.
702.36f If a permanent’s morph cost includes X, other abilities of that permanent may also refer to X. The value of X in those abilities is equal to the value of X chosen as the morph special action was taken.
702.36g See rule 707, “Face-Down Spells and Permanents,” for more information about how to cast cards with a morph ability.
From the glossary of the Comprehensive Rules (July 12, 2019—Core Set 2020)
Megamorph
A variant of the morph ability that puts a +1/+1 counter on the creature as it turns face up. See rule 702.36, “Morph.”
707. Face-Down Spells and Permanents
707.1. Some cards allow spells and permanents to be face down.
707.2. Face-down spells and face-down permanents have no characteristics other than those listed by the ability or rules that allowed the spell or permanent to be face down. Any listed characteristics are the copiable values of that object’s characteristics. (See rule 613, “Interaction of Continuous Effects,” and rule 706, “Copying Objects.”)
707.2a If a face-up permanent is turned face down by a spell or ability that doesn’t list any characteristics for that object, it becomes a 2/2 face-down creature with no text, no name, no subtypes, and no mana cost. A permanent that enters the battlefield face down also has these characteristics unless otherwise specified by the effect that put it onto the battlefield face down or allowed it to be cast face down. These values are the copiable values of that object’s characteristics.
707.3. Objects that are put onto the battlefield face down are turned face down before they enter the battlefield, so the permanent’s enters-the-battlefield abilities won’t trigger (if triggered) or have any effect (if static).
707.4. Objects that are cast face down are turned face down before they are put onto the stack, so effects that care about the characteristics of a spell will see only the face-down spell’s characteristics. Any effects or prohibitions that would apply to casting an object with these characteristics (and not the face-up object’s characteristics) are applied to casting this object. The permanent the spell becomes will be a face-down permanent.
707.5. At any time, you may look at a face-down spell you control on the stack or a face-down permanent you control (even if it’s phased out). You can’t look at face-down cards in any other zone or face-down spells or permanents controlled by another player.
707.6. If you control multiple face-down spells or face-down permanents, you must ensure at all times that your face-down spells and permanents can be easily differentiated from each other. This includes, but is not limited to, knowing what ability or rules caused the permanents to be face down, the order spells were cast, the order that face-down permanents entered the battlefield, which creature(s) attacked last turn, and any other differences between face-down spells or permanents. Common methods for distinguishing between face-down objects include using counters or dice to mark the different objects, or clearly placing those objects in order on the table.
707.7. The ability or rules that allow a permanent to be face down may also allow the permanent’s controller to turn it face up. Spells normally can’t be turned face up.
707.8. As a face-down permanent is turned face up, its copiable values revert to its normal copiable values. Any effects that have been applied to the face-down permanent still apply to the face-up permanent. Any abilities relating to the permanent entering the battlefield don’t trigger and don’t have any effect, because the permanent has already entered the battlefield.
707.9. If a face-down permanent moves from the battlefield to any other zone, its owner must reveal it to all players as they move it. If a face-down spell moves from the stack to any zone other than the battlefield, its owner must reveal it to all players as they move it. If a player leaves the game, all face-down permanents and spells owned by that player must be revealed to all players. At the end of each game, all face-down permanents and spells must be revealed to all players.
707.10. If a face-down permanent becomes a copy of another permanent, its copiable values become the copiable values of that permanent, as modified by its face-down status. Its characteristics therefore remain the same: the characteristics listed by the ability or rules that allowed it to be turned face down. However, if it is turned face up, its copiable values become the values it copied from the other permanent. See rule 706.3.
707.11. If a face-down permanent would have an “As [this permanent] is turned face up . . .” ability after it’s turned face up, that ability is applied while that permanent is being turned face up, not afterward.
708. Split Cards
708.1. Split cards have two card faces on a single card. The back of a split card is the normal Magic card back.
708.2. Although split cards have two castable halves, each split card is only one card. For example, a player who has drawn or discarded a split card has drawn or discarded one card, not two.
708.3. A player chooses which half of a split card they are casting before putting it onto the stack.
708.3a Only the chosen half is evaluated to see if it can be cast. Only that half is considered to be put onto the stack.
708.3b While on the stack, only the characteristics of the half being cast exist. The other half’s characteristics are treated as though they didn’t exist.
708.3c An effect may create a copy of a split card and allow a player to cast the copy. That copy retains the characteristics of the two halves separated into the same two halves as the original card. (See rule 706.12.)
708.4. In every zone except the stack, the characteristics of a split card are those of its two halves combined. This is a change from previous rules.
708.4a Each split card has two names. If an effect instructs a player to choose a card name and the player wants to choose a split card’s name, the player must choose one of those names and not both. An object has the chosen name if one of its names is the chosen name.
708.4b The mana cost of a split card is the combined mana costs of its two halves. A split card’s colors and converted mana cost are determined from its combined mana cost.
Example: Assault/Battery’s mana cost is {3}{R}{G}. It’s a red and green card with a converted mana cost of 5. If you cast Assault, the resulting spell is a red spell with a converted mana cost of 1.
708.4c A split card has each card type specified on either of its halves and each ability in the text box of each half.
708.4d The characteristics of a fused split spell on the stack are also those of its two halves combined (see rule 702.101, “Fuse”).
