I wrote this song for someone on Equestria Amino.
http://aminoapps.com/p/8syars

Image Source:
https://www.google.ca/search?q=night+background&client=ms-android-bell-ca&prmd=ivn&source=lnms&tbm=isch&sa=X&ved=0ahUKEwi-vvOf_vDXAhUCyWMKHdMRAUEQ_AUIESgB&biw=598&bih=280#imgrc=Yz4blp5ywkslkM


Lyrics:

(Celestia)
Luna, please dont do this

We can rule together

Please dont make a desiciom that

You could regret forever


(Nightmare)
But I have the power

To control both night and day

You're more important

Why can't I have my way?


(Celestia)
But we all need you

You are the one who rules the night

If you don't stop now

I'll have to put up a fight


(Nightmare)
Bring it on!


-Celestia and Nightmare fight until Celestia is hit and falls-


(Celestia)
I wish we could be together

Rule Equestria you and me

But I have no choice but to use the Elements of Harmony



-Celestia flies up to Nightmare with the Elements circling her-


(Nightmare)
You are making a big mistake!


(Celestia)
This is too much for you to take


(Celestia)
I'm sorry I have to.

I must banish you to the moon.


-Celestia banishes Nightmare Moon to the moon-


(Celestia)
Maybe someday, she'll change

And change her ways

Mabye someday