Mystic shot may still scale with AP, but it deals physical damage. Skills that deal physical damage are unaffected by spell shields (or at least, that's what I'm guessing).
Edit: Why the hell did riot move this to guide's and strategy?
oh wow, I kept trying to remove the BV shield with his w before using q, thanks for info.
© 2013 Riot Games, Inc. All rights reserved. Riot Games, League of Legends and PvP.net are trademarks, services marks, or registered trademarks of Riot Games, Inc.