One of my players wants to know if when he casts a spell that requires a will save, and it succeeds, if he knows that the spell didn't work. To give more context, the spell in question is True Form. He wants to know if his caster knows when it doesn't work versus the target just not having any other form to reveal, though this can apply to some other more subtle spells.
It's of my opinion that, no, he shouldn't know whether or not a spell succeeded but I can see his point. Other spells you can tell at a glance whether they worked or not (Charm Person, for example.)
I wouldn't mind some thoughts/opinions on the matter.
