After reading your posts, and toying with the character creator a bit I have a suggestion to put forth.
Kinetic Melee/Super Reflexes
Both powersets seem to match with your concept. Motion is possibly the most universal force in existence, one could argue that it is the ONLY force, as all forms of energy involve something moving. As such your Entity would be intimately aware of how it affected the physical world she want's to operate in.
Also, being omniscient, she would be aware of all attacks before they landed, making it easy enough to simply move out of the way. The few times she gets hit could easily be explained as part of her uncaring nature, she just didn't feel like moving that time.
As far as costumes go, I think the Bioluminescent skin makes for an intersting under-layer. With creative coloring you can give the impression that her power, even imprisoned, is too great to be fully contained by a mortal, physical shell.
