208.1. A creature card has two numbers separated by a slash printed in its lower right corner. The first number is its power (the amount of damage it deals in combat); the second is its toughness (the amount of damage needed to destroy it). For example, 2/3 means the object has power 2 and toughness 3. Power and toughness can be modified or set to particular values by effects.
208.2. Rather than a fixed number, some creature cards have power and/or toughness that includes a star (*).
208.2a The card may have a characteristic-defining ability that sets its power and/or toughness according to some stated condition. (See rule 604.3.) Such an ability is worded “[This creature’s] [power or toughness] is equal to . . .” or “[This creature’s] power and toughness are each equal to . . .” This ability functions everywhere, even outside the game. If the ability needs to use a number that can’t be determined, including inside a calculation, use 0 instead of that number.
208.2b The card may have a static ability that creates a replacement effect that sets the creature’s power and toughness to one of a number of specific values as it enters the battlefield or is turned face up. (See rule 614, “Replacement Effects.”) Such an ability is worded “As [this creature] enters the battlefield . . . ,” “As [this creature] is turned face up . . . ,” or “[This creature] enters the battlefield as . . .” and lists two or more specific power and toughness values (and may also list additional characteristics). The characteristics chosen or determined with these effects affect the creature’s copiable values. (See rule 706.2.) While the card isn’t on the battlefield, its power and toughness are each considered to be 0.
208.3. A noncreature permanent has no power or toughness, even if it’s a card with a power and toughness printed on it (such as a Vehicle). A noncreature object not on the battlefield has power or toughness only if it has a power and toughness printed on it.
208.3a If an effect would be created that affects the power and/or toughness of a noncreature permanent, that effect is created even though it doesn’t do anything unless that permanent becomes a creature.
208.4. Effects that set a creature’s power and/or toughness to specific values may refer to that creature’s “base power,” “base toughness,” or “base power and toughness.” Other continuous effects may further modify the creature’s power and toughness. See rule 613, “Interaction of Continuous Effects.”
208.5. If a creature somehow has no value for its power, its power is 0. The same is true for toughness.