Image imported from derpibooru 
Original Description:
 
The Witch’s Mistake - Halloween-themed YCH auction!
 
Bid here: https://ych.art/auction/59595
 
SB: $35  
MI: $5  
AB: $200
 
Female/Futa characters only.  
MLP pony-like characters only (all main pony races, zebras, bats, kirins).  
If the winning bid gets up to or over $60, there will be two versions: nude and wearing the suit mentioned in the short story below. The example picture shows the suit version. Below $60 only the nude version will be done.
 

 
Your house and garden are full of enormously large pumpkins for every Halloween, just like this time.
 
Others fear to get close to your place, especially at those times. They spread rumors about you practicing dark magic - and they aren’t wrong.
 
Usually you just keep having fun your weird ways, just finding it appropriate to dress up in carefully made costumes of various kinds and mess around, scaring other citizens of your town, just as appropriate for the time. October has long become the best month of the year for you.
 
Though, this year you decided to try something new. Your new costume was pretty simple this time, just a skintight suit with some geometric patterns, much similar to a diving suit, at least for now. To turn your costume into what you wanted it to be you have went an extra mile and prepared a potion from an old magic book you have found just recently.
 
The potion had to be made in big volume in a huge vat in order to work as you wanted it to, on the costume and your whole body. According to the instructions both the wearer and the attire had to be submerged for a certain amount of time. Though it was not mentioned if the wearer should have their soon-to-be-enchanted clothing on or it should be done separetely.
 
Either way, the potion was ready, slowly boiling, in fact very slowly… It almost looked like dark goop. Would be hell of a thing to dispose and wash after if it stays like this after use… But the promised effects seemed to be worth it.
 
So you have leaned down from your convenient pumpkin seat which you made to work on such large vat easier, to try touching the slowly boiling dark liquid. Once you did, the sticky substance latched on to your fingers, not letting go despite you quickly pulling back up. It wouldn’t let go, stretching and pulling down. You managed to resits the pull, but not the spread, as the black substance kept crawling up your arm, some of it reached your hoof and began working up along the leg too, also holding it down.
 
The more it spread, the more it pulled, the harder it was getting for you to resist or move at all. At some point your body gave up and you dropped into the black gooey potion headfirst, quickly sinking down, still struggling…
 

 
After this night nobody has seen the odd mare anymore. Ones who lived in nearby houses reported that at the night before the “witch mare” disappeared, rather loud, yet often muffled moans and groans could be heard from her house for the whole nighttime… But nobody has seen her since, not even got close to her house, seemingly with nothing changed about it. For the better, as they all thought…