Changeling

Changeling is a characteristic-defining keyword ability. It only appears on shapeshifter cards and grants those cards all creature types.

History
Changelings were featured in the Lorwyn block; the design was based on Mistform Ultimus' ability. Creatures with changeling reappeared in Modern Horizons, where the mechanic likewise was used to make a cohesive set. They were focused in White and Black in an unusual "arbitrary tribal" archetype, where many lords were printed that only had Changelings to work off. The set also brought the first artifact and colorless changelings.

They returned again in Kaldheim. This time they were focused in Blue and Green.

Rulings

 * Because a card with changeling is every creature type, it will be affected by any spell or ability that affects any creature type, regardless of what that creature type is. And because changeling is a characteristic-defining ability, this is true in all zones. For example, if a card tells you to reveal a Merfolk card from your hand, return a Goblin card from your graveyard to your hand, or gain control of a Goat, you can perform these actions on a card with changeling.
 * The rules that govern the interaction of continuous effects state that type-changing effects are applied before effects that add or remove abilities. This causes some unusual things to happen.
 * If an effect causes a creature with changeling to lose all creature types, the creature won't lose changeling—but it will lose all its creature types.
 * If an effect causes a creature with changeling to become a new creature type or types, the creature won't lose changeling—but it won't have all creature types anymore. It will be just the new creature type(s).
 * If a card loses the changeling ability, it will still have all creature types. It just won't have changeling.
 * Similarly, if an object gains changeling, it will not gain any new creature types, but it will still have changeling.


 * Note that effects that grant an object all creature types do *not* give that object changeling.