@Tarith: You attack the giant, but do not fell him. This time, they find Nerine's behavior too suspicious. The giant returns in kind.
Attack1: (1d20+16) miss chance (1d100)(65) damage (2d8+10)
Attack2: (1d20+11) miss chance (1d100)(15) damage (2d8+10)
"You're not Mistress Nerine. I should have known!"
I know, spell indicates otherwise, but you need some action on your side as well. Besides, even for her, it would be too suspicious. And bluff only gets you so far.