Was looking around at monk abilities as they level, and noticed this little gem:
Empty Body (Su): At 19th level, a monk gains the ability to assume an ethereal state for 1 round per monk level per day, as though using the spell etherealness. She may go ethereal on a number of different occasions during any single day, as long as the total number of rounds spent in an ethereal state does not exceed her monk level.
Think this makes it in?