Shield Magic Attack 60%. Where does it drop from?

They don't drop from those mobs anymore. As I recall, due to the Sakura Castle makeover, all such scrolls for shield for MA/WA have been removed from the droptables of those monsters. You can cross-check with the monster book.

GL. edit: oh yeah, AFAIK all open-drop monsters (i.e. those in the monster book) don't drop those scrolls either. And none of the SG/MY monsters drop them either.

Hadriel

Well, that's reassuring lol. What about the 30% or 70% versions? Do those not drop anymore either?

Chances are your seller simply has a huge stack of them somewhere, and is only putting one in the shop at a time to be able to price them high due to scarcity.

I guess there's a good chance that's happening.