Clarify, I didn't quite understand what exactly you want to know.
Blasphemy - well, like, you choose some BELIEF for yourself, and then you do something that contradicts it, how will this be reflected?
If the plot requires me to have the character perform certain actions, the character will perform them regardless of the player's desire.
a) he is somehow mind-controlled by something like that -> plot-wise
b) simply the fact of performing the action, regardless of the reasons and everything else -> mechanically
Probably the second one, judging by your answer.
Added 2 minutes ago
Okay, fine, let it be possible, if you really want it.
Added 4 minutes ago
Masquerade (70) The Sorcerer gains the ability to change his or another's appearance.