This article reveals some plot points in the film
Legend of the Black Scorpion.
Several people have been referred to my review in ACF 079 when they ran searches that asked, in essence, "Who killed Empress Wan in Legend of the Black Scorpion?" I didn't discuss the matter in my review, but since there seems to be at least a fair amount of interest in the question, here goes.
The short, and correct, answer is that the film does not reveal who kills Empress Wan (Zhang Ziyi) at the end of the film. Neither Feng Xiaogang, the director, nor the cast have said. In his interview on Disc 2 of the Dragon Dynasty DVD release, actor Daniel Wu (Prince Wu Luan) teasingly says that he knows but won't tell.
My thought, when I first saw the film at the 2007 New York Asian Film Festival, was that it was the ghost of the dead Emperor, Prince Wu's father, who killed her. I mean, if his armor can bleed, why couldn't he strike her down after all the misfortune that she'd caused, even if she didn't do it deliberately?
One of the members of Subway Cinema, the organization that sponsored the festival, told me that he thought it was Minister Yin, who had been sent into exile by the Empress. The logic here was that he was the only significant character that was still alive. Turns out this was close to the mark.
Bey Logan, in his terrific commentary accompanying the movie on Disc 1, discusses what he knows, and sheds considerable light on the vexing question. According to him, the script originally called for the one maid who is seen in several shots throughout the film (she's in the background in the screen shot above) to kill the Empress. Furthermore the murder was done at the bidding of Minister Yin, who certainly had motives.
I believe Logan also said that scenes that would have given the maid greater presence, and perhaps some that actually showed the order being given and the deed being done, either were not shot or were deleted when the director decided to make the ending ambiguous.
So there's the best answer available that I know of. As Logan delightfully puts it: "It was the maid what done it."