magic gathering changeling hand

[Muk]

does changeling work when card is in your hand?

[Arix]

The card says "at all times", and it really means it. Whether in your hand, library, graveyard, exiled, or not even part of the game, a changeling is all creature type.

Basically you can treat it as though it actually had every single creature type on the type line. In really, really small font.