there's a good villainess

Too many villains spoil the climax. . . .

Fortunately, the villainess I was thinking of as the chief one reveals that she will be taking a number of the others out of the way.  And that will make her more dangerous for the climax.  How handy!

Meanwhile, some of the others have to vanish by more ordinary means.

Now, I just have to decide whether she does it on stage, or reveals it at the end.  The first builds dramatic irony but the second gives a bigger twist, assuming that I can foreshadow it enough.