Used and Credited https://www.deviantart.com/bronybyexception/art/2023-Advent-Day-23-1004445020

the source of such fanart has been revived

She’s got wings (and a horn) of fury

@Background Pony #2949  
Why would you think that? Why would she?

Protective Princess mode: INGAGE!

But, what if she hits her aunt?1

@Background Pony #AAD5  
I think Flurry Heart already knows how to not fall.

well is normal for equestria princess want proctect their kingdom! those who mess with one princess is mean you get hurt! flurry a learn by Twilight for control her magic and and she to fight by her daddy! she learn to share and love by her mother! she learn to be a great princess by celestia! luna teach her to not fall to the madness for not become a monster like luna a turn one!

@Background Pony #F953
 
@Strawberry_Mask  
Yeah, considering that they’re both princesses, daughters of a honorable dorky blue-haired princes, very powerful, and both are adorable babies. :3

@Strawberry_Mask  
So true; I don’t know why, but I constantly found myself comparing Flurry Heart and Lucina

@FillyFondlerFun
 
Okay I will

She looks like a formidable little thing…

I now have a headcanon that when Fluury reaches the teens, she will try to change her name to “Fury Heart”.  
“But dad, it sounds sooo much cooler! Flurryyy…. ugh, lame, lame, lame!”

“Fury Heart” sounds like a power metal song.

And here we have the equestria version of lucina

Fury Heart, Warrior Princess

@MeshGearFox  
I really like the idea that some bacteria actually live of the magical waste products and produce reusable magic energy for the host. A unicorn with a rich bacterial culture could make much stronger spells before their body start taking damage from toxins and get less tired because the bacteria turns some of the waste magic back into reusable magic.
 
This would also have the interesting effect of making antibiotics dangerous for ponies. If they destabilize their gut flora, their magical reserve is decreased and they’re more susceptible to magic poisoning.
 
I could imagine that the way magic bolts work is by inserting raw, volatile magic into the targets body and basically kill them from the inside out. They could cause magic poisoning and prevent them from casting strong spells because they’re already saturated with toxins.
 
Maybe there could even be hostile bacteria that would do the opposite, consuming a ponies magic reservoir and producing toxins as a waste product. If they started out competing the healthy, toxin eating bacteria it could seriously hurt ponies to the point were it might even kill them. Kinda ironic that the only real way to keep them safe is by completely isolating them from magic in a world were it’s abundant.

“CALL ME A FRIGGEN MARY SUE ONE MORE TIME”

@FillyFondlerFun
 
Honestly I just thing gill-wings would be neat in a Nightmare-mode pony cause they sort of go with the corruption buuuuuuut…
 
Now I got another idea – when ponies use magic, they increase the amount of ambient ‘loose’ magic around them, both from whatever magical waste product is exhaled/evaporated via sweat as well as magic that’s kind of… just leeched out of the horn without really being directed/otherwise lost due to /inefficiencies/.
 
Anyway, so Nightmare-mode Flurry Heart (Fury Heart, w/e) has these gill-wings which are used to basically recapture this loose magic and magical waste so that she can remetabolize it into usable magic, allowing for more sustained usage of stronger magical abilities.
 
(Idea 2: Pegasi have mutualistic wing bacteria that do something similar on a smaller scale. And because of this pegasi can’t… idk use shampoo on their wings because it’ll screw up their wing flora and they’ll lose endurance).
 
(Idea 3: Unicorns have special gut bacteria that are necessary for getting magical energy from food, and you could effectively shut down a unicorn by feeding them like idk too much kefir or something with /live active cultures/ that would out-compete the magical bacteria.
 
Magic spikes in nursing unicorn foals is related to this too I guess!)

@MeshGearFox  
Well that’s an interesting idea. I could imagine something where magic is produced in the muscles and is channeled to the horn or a pegasus’s wings or earthpony hooves. Now that I think about it, it actually makes a bit of sense since in the show we sometimes see energy flowing through the entire pony body when they cast really large spells (like the S4 final).
 
And your idea with waste products I find REALLY interesting. Like a little bit of magic does no harm but channel to much and it might start a chemical reaction that releases toxins into the bloodstream (that’s at least how I imagined it). If they’re careless they might even be able to hurt or kill themselves.
 
I’m still not entirely convinced about the thing with the wings and gills. I’d imagine they just sweat it out and larger wings allow a pony to secret more toxins.

@FillyFondlerFun
 
Naturally you have copper heat pipes attached to the horn via thermal paste, and those run to the wings. To like, conduct the heat.
 
But nah I’m assuming the heat would be generated inside her body, not in the horn. The horn would get hot from the magic sure, but I’d expect some /magically metabolic process/ going on inside of her torso region would be generating most of the energy and heat to power said magic.
 
If I wanted to take the wings-as-gills things further, I’d say they also had something to filter /loose magic/ or some other energy source out of the air, too.
 
Actually let’s run with this further – let’s say using magic generates some other waste component that would usually be exhaled out, but if you’re using a sufficient amount of magic it would build up in your muscle tissue and just /hurt like the dickens/. So the wings in this case would… draw in loose magic/act like solar panels/wevz, draw in energy that would be converted into focused magic via some gut-region wizard horse organ, channeled magic would be conducted out through the horn (or maybe stored in some buffering organ thing behind the horn), and then the excess heat and waste magic would exit via the wing-gills.

@MeshGearFox  
I’m not quit sure how you imagine the wings would work as heat radiators. The magic energy is concentrated in the horn so that’s the only real place the heat can radiate from. For the wings to work as radiators the body would somehow have to transport the heat through the body and down to the wings which wouldn’t be very efficient and could potentially be dangerous to Flurry if channeling a lot of magic.
 
The only thing that would work is to increase the length a girth of the horn itself to increase surface area, enabling it to radiate more heat.
 
I don’t wanna sound pedantic, I do like your overall idea though. You seem to have the basic concept down but unless the energy was produced in the center of the body and not the horn, I don’t see how this would work.

btw I had another idea for nightmare-mode Flurry Heart (sort of inspired by something from Eva or Snowcrash I think?):
 
She can shoot huge magical blasts from her horn, but they generate massive amounts of heat. Cue the huge wings: In nightmare mode, they act like radiators somehow (thinking some kind of gills instead of normal feathers. They wouldn’t be great for flying in Nightmare Mode, but that’s not the point).

@MeshGearFox  

 
Make this a tag pls.

Also, Nightmare-mode Flurry Heart is Fury Heart.