Sylvester Archipelago

Is this a game of shadows and light, or a change in facial (and body) structure? Permanent or temporary?

It's a game of shadows and light. Changing the structure of the face (and body) is too much for you, but I'll let you in on a secret: some mages can do that.
Of course, it will be temporary and will depend on the strength of will. And naturally, an NPC with a strong will will see that you've conjured up a new face for yourself.