Eccentric Apprentice (AFR) from Adventures in the Forgotten Realms, available at 401 Games Canada.

• Rarity: Uncommon
• Finish: Normal
• Artist: Campbell White
• Card Text:
  Flying
  When Eccentric Apprentice enters the battlefield, 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.