Weird astomoi question

[Fae]

So if an astomoi takes the umbral unmasking drawback trait does it 1 cease to exist 2 become invisible or 3 just look scary since they are made out of shadows

[Feantar]

So if an astomoi takes the umbral unmasking drawback trait does it 1 cease to exist 2 become invisible or 3 just look scary since they are made out of shadows

Well, at least checking at pfsrd:

Astomoi appear to be made of pure darkness

Keyword, appear. They are not actually made of pure shadow.Therefore... nothing. They just don't have a shadow, or their shadow looks monstrous, as everyone else.

Now if a Shadow were to take umbral unmasking... :P