Mist Dragon

{0}: This creature gains flying. (This effect lasts indefinitely.) {0}: This creature loses flying. (This effect lasts indefinitely.) {3}{U}{U}: This creature phases out. (While it's phased out, it's treated as though it doesn't exist. It phases in before you untap during your next untap step.)

From Magic: The Gathering.

Open the interactive version on https://mythscribe.cloud/app/tcg/cards/cms6o8o195kfvpb1hvjg7d2lh.