So I was very pleasantly surprised at how well-received my last little doodle with Discord and Celestia was, so I figured I’d go and make some full-body refs of their pony disguises.
 
Oh man it’s been a hot second since I’ve drawn horse anatomy.
 
Anyhow, onto a few headcanons!
 
 
Discord’s pony disguise is lanky, with mule-like ears and a funny, squiggle-shaped horn. He looks a bit different from your average pony, but it’s a good enough disguise to get the job done. He doesn’t like to take this form often and will only do so unless absolutely necessary (or maybe if Celestia asks nicely and promises to let him fill the palace with banana peels afterwards, either or).
 
His cutie mark is a tornado, based off that one episode with Tirek where Discord disguised himself as a pony with a tornado cutie mark.
 
 
Celestia’s disguise is perfect rendition of an average pony. She poses as a fruit salespony, with her cutie mark being an orange. Discord finds it rather amusing, the head princess of Equestria posing as a regular little orange farmer, but Tia simply likes the simplicity of it all. Nopony would ever expect her to be a royal in-disguise, which is the entire point of these illusion spells.
 
 
Overall, illusion spells like these are pretty much only used if there’s a threat that requires an undercover mission to be taken care of (see: Discord going after Tirek), but Tia has been known to use her disguise to go out and just mingle with other ponies. She likes being able to know her subjects on a more personal level, plus it can be a great stress reliever when she needs just a tiny break from running the kingdom.