Characteristic-defining ability

A characteristic-defining ability is a kind of static ability that conveys information about an object's characteristics that would normally be found elsewhere on that object (such as in its mana cost, type line, or power/toughness box).

Characteristic-defining abilities are noteworthy because they are active at all times, even while not in play or outside of the game.

Characteristic-defining keywords are:

• Changeling (grants every creature type.) e.g. Avian Changeling.
• Devoid (makes an object colorless, despite the presence of colored mana in the mana cost) e.g. Touch of the Void.

Other examples are:

• Transguild Courier has an ability that makes it all colors.
• Veteran Adventurer has an ability that makes it a Cleric, Rogue, Warrior, and Wizard in addition to its other types.

Rules

From the glossary of the Comprehensive Rules (April 12, 2024—Outlaws of Thunder Junction)

Characteristic-Defining Ability

A kind of static ability that conveys information about an object’s characteristics that would normally be found elsewhere on that object (such as in its mana cost, type line, or power/toughness box). See rule 604.3.

From the Comprehensive Rules (April 12, 2024—Outlaws of Thunder Junction)

• 604.3. Some static abilities are characteristic-defining abilities. A characteristic-defining ability conveys information about an object’s characteristics that would normally be found elsewhere on that object (such as in its mana cost, type line, or power/toughness box). Characteristic-defining abilities can add to or override information found elsewhere on that object. Characteristic-defining abilities function in all zones. They also function outside the game and before the game begins.
  • 604.3a A static ability is a characteristic-defining ability if it meets the following criteria: (1) It defines an object’s colors, subtypes, power, or toughness; (2) it is printed on the card it affects, it was granted to the token it affects by the effect that created the token, or it was acquired by the object it affects as the result of a copy effect or text-changing effect; (3) it does not directly affect the characteristics of any other objects; (4) it is not an ability that an object grants to itself; and (5) it does not set the values of such characteristics only if certain conditions are met.