Well, with melee build which specializes to be sneaky the sudden strike +4d6 is nice, and able do melee touch attacks and ignore concealments. Not sure do you get from one templates ability see in darkness (so far as I know your going to demon side and so your obyrith subtype would only grant true seeing which is limited to 60'ft range).<br/><br/>Anyways if you go obyrith it's important to develop form of madness what you provoke. Considering your stealthy and shadow/darkness theme then would it create achluophobia (http://en.wikipedia.org/wiki/Fear_of_the_dark) perhaps? If you get somehow ability create darkness or deeper darkness it would be devastating (but it can be devastating to used at night where it's dark already).