Request: Coverimage in exchange for a Oneshot of your wish

Hello everyone.
I am thinking about getting a proper coverimage for my fanfiction Lunar Sin. Because I am not the best drawer and do not have a program for digital art or know, how to draw digital art, I was wondering, if somebody, who is a good artist, would like to draw the cover of Lunar Sin.
I have to state this now, before anyone complains: I know, drawing something takes time and many redoes. I value that and I can understand that artists want to be paid for their work. Sadly I do not know, how to pay an artist. Therefor I decided that I will use a Oneshot as a payment. This means, you draw the cover image and I will write a Oneshot for you, that is between 1000 and 4000 words long. You have the right to tell me, which characters should appear in this Oneshot, where the scenario takes place and what should happen in one sentence.
If you draw the cover image, there should be the following aspects in it:
- Princess Luna
- Nightmare Moon (as a seperate being from Luna)
- Princess Celestia
- the Elements of Disharmony (this means not the discorded Mane Six, but six gemstones, similiar to the Elements of Harmony, but in other colours)
If you are interested in this task and kind of deal, feel free to PM me, so we can discuss the subject. If you have DeviantArt, you can upload the cover image there, so I can tell in the describtion of Lunar Sin, who provided the cover image.
I really hope, somebody could do the cover for me.
With respect and hope,
your Noctus Noxia