Eccentric Apprentice (Adventures in the Forgotten Realms)

Creature Ñ Tiefling Wizard - Flying
When this creature enters, venture into the dungeon. (Enter the first room or advance to the next room.)
At the beginning of combat on your turn, if you've completed a dungeon, up to one target creature becomes a Bird with base power and toughness 1/1 and flying until end of turn.