Dear Princess Celestia,
So, Princess, are you ready for Nightmare Night? Oh, it's early, but it's never too early for creatures like you and me. Do you have your costume picked out? It's not very long now. Are you going to do the same thing as the last four hundred and thirty seven years and just spend the entire time hiding in your palace while leaving your sister to deal with the common pony? A very exclusive source has let me know that she plans to visit Ponyville. Oh, don't even think about going along, you'd just cramp her style—but how do you think she'll feel when she learns that you don't even take part in this ridiculous little holiday that you invented in her name?
If you can't come up with anything at all, you could always turn to me. Your sister can attest to the disguises I can make even for you ponies. Wouldn't it be interesting to get out among the common folk? Why, you could even even try to get a proper understanding of what the common pony thinks of your sister on this, the one special day of the year you've designated to single her out for fear and hatred.
As for me, I was thinking that I might try 'changeling' for a costume. It's the kind of look that would really become me, you know?
I will give you a moment here to put your head in your hooves and murmur to yourself: 'Chrysalis, no.'
Now we shall continue my rebuttal: Chrysalis, yes. This can be our little soft introduction, with your ponies so inclined on Nightmare Night to look at anything out of the ordinary as a trick or costume.
And just think: you'll finally get to find out what we look like.
Yours in childish frights,
Queen ChrysalisP.S. 'Nightmare Night' is certainly catchy, but you really should have tried to push for a less specific theme.