Hi, readers!
I’m a little behind, so I have to leave you with this observation:
One of the worst things a science-fiction writer can do is to introduce an amazing technology or alien ability, and then do nothing with it.
I was reminded of this when watching Attack of the Clones with my kids. Zam Wessel is chased down by Obi-Wan and Anakin, and under stress begins to revert to her true shape. Anakin recognizes that she is a Changeling.
And then, she utterly fails to change her face, attempting to sneak up on Obi-Wan disguised as the same attractive woman she was when they started chasing her. The whole thing goes nowhere, and we’re left with a terrible sense of disappointment. Never do that to your readers. It’s like going to a banquet and finding out that the delicious dessert in the center of the table is a frosted cardboard prop.
So, the reason I’m behind is that I’ve spent the last month (and a VERY intense last WEEK) revising a 620-page novel and have just sent it to a publisher. I’m done writing today.
G. Scott Huggins 
Sounds like the Time-Turner, or James Potter’s identity as an animagus, in the Harry Potter books. Those (from “Prizoner of Azkaban”) were about the worst in that series, but there were more. Such Irish Pennants of prose rather weaken their stories, instead of strengthening them.
The only exception I can think of is E. E. Smith’s “Chekov’s gunstore” approach. Introduce so many cool things in such an offhand manner that the *whole galaxy* is too cool for words.
That may be what Lucas was trying for. If so, he didn’t think it through. Chekov’s gunstore requires *gratuitous* cool stuff. A shapechanging assassin is not gratuitous.