If you like spell-like abilities, then any or all in the line of Silent/Minor/Major/Persistent Image spells could work, also possibly Shadow Conjuration. Though it's REALLY powerful, giving a demon-like ability to see in magical darkness would also fit.
For supernatural shadow stuff, summoning darkness to improve hide rolls would fit well, so would something like a constant change/alter self spell. I only have a passing knowledge of white wolf Vampire games, but the Lasombra clan has a discipline called Obtenebration, which is manipulating shadows and shadow-stuffs. You could maybe also find inspiration there.
-nameless