It's cliché but what do you (does everyone) think of a Sue Richards metamorphosis for Black Widow.

Natasha would remain a crack assassin but be able to turn invisible and either skate around on invisible waves or shoot invisible rays or both. The invisible rays are my choice to stay. The rays would be absorbable and not cause too much damage. Then, there's the force field. It won't be on Invisible Woman's scale, but it can stop a bullet or a medium energy bolt. Input?

She will be who she's always been. I'm going to look up several histories to use as source material for her history. And, as far as her personality goes I think I'd define her as optimistic, realistic, fast, and stable and well enough to cover her own ass.