So one of the sorcerer's metamagic abilities is the "subtle spell" ability (pg 103 PHB). How does this interact with the campaign "casting spells with subtlety" description on page 39 of the primer? I would assume it automatically meets the requirement for subtle casting (though not necessarily for subtle effect, of course). As a matter of fact, I usually see it played as there is no sign of casting at all if you use it on an invisible type of spell, like charm person. I figure that in a world with such obvious use for the ability, it should be clearly spelled out if it meets the requirements. Mileage at individual tables shouldn't vary.