disclaimer: Hasbro owns Princess Luna, Starswirl the Bearded, Princess Celestia, Equestria, and some other things and characters I've forgotten to mention. The rest of the ponies and ideas in both the following description and the picture itself are owned by someone else, I just wish I could remember who it was. I own only the villain names and concepts I've created, in addition to any other concepts I have come up with.
Thank you Madmax for the wonderful picture...
The following is to explain the picture, and more generally capture how awesome I think Princess Luna is. The rest of the description will be posted at some point in the future:
When most beings think of Equestria they think of only one half of it, the half called "Escurara", though few would call it that these days. The more obscure part is known as Ponyland. The two parts of Equestria our as different as the domains of the two Royal Sisters.
Escurara is home to cities that are older than the sisters themselves, it is settled (comparatively), as many unicorns, has only a few notable magical objects, has few non-pony residents, is relatively safe and carefree compared to other powerful nations, does not require a Guardian, and all ponies know Princess Luna for is raising the moon at night and little else.
Ponyland has ancient temples and a city or two that are older than the sister's mentor (a deity, 19,000 years old), largely unsettled by ponies, has very few unicorns, has many powerful and well-known magical objects, such as the Golden Horseshoes, the Flashstone, the Golden Rose, and the Sunstone, is mostly settled by non-ponies (Mostly elves but also: Scree, Blarks, Trolls, Tadswamp's, Golem's, Goblins, Bushwoolies, Anthophila (Bees), Troggles, Karkinos, Flutterponies, Jhipon-Nixies (Seaponies), Gnomes, Breezeies, Piggs, Gizmonks, Dell Dwellers, Grundles, and more), was once threatened by horrifying evils, needed a guardian or hero badly, AND knows Princess Luna as their greatest warrior, Equestria's greatest lawmaker, a brilliant fighter of crime, and most of all the Great Protector of Ponyland!
The delegation from the rulers presented them an extraordinary deal: Ponyland would become first a protectorate of, then a part of Equestria in exchange for both a powerful warrior to protect the land from the reemerging collection of black magic users, witches, and demons that threatened the land and a powerful being who would be an arbitrator between the kingdoms. Powerful beings like the Flutterponies, gnomes, Seaponies, Gnomes, and the Princess ponies (who were the immortal guardians of one half of the planet’s magical energy) were skeptical that there was a warrior in Equestria strong enough to fight the terrifying magical threats involved. Princess Luna, having grown bored of being simply a lawmaker, night-sky designer, occasional crimefighter, and problem solver, asked for and received the task.
Therefore a week later after fine tuning her ability to use the elements without the aid of her sister, which she gained due to an accident at the private coronation of both princesses in front of the unbelievably powerful magic gem known as the "Heart of Ponyland" where Luna hit her horn against the large diamond by accident thus allowing her to use the elements without the aid of her sister, Luna went with 30 of the best night and day guards to shut down a rumored meeting of group of strange magic using witches. Upon arriving at the suspected location and time of the meeting Luna and the guards silently observed a gathering involving the telling of past miscreants. The assembled beings called themselves the "Hydorchaos" Witch-Clan. This group of beings have been created by Discord as part of a plan to bring him back in case a powerfull being managed to defeat him and seal him away, due to the nature of chaos energy and magic, the plan hadn't worked and the witches had no intention of even trying to free Discord, they did however name drop him a lot.
A few seconds after the meeting was over Luna and the rest of the guards stepped out of the shadows and after making a short speech Princess Luna and the guards charged at the clan however all of its members, except one, teleported away into the night. The remaining witch was the most powerful of the lot. She was the clan's founder and the first witch created by Discord and her name was Alexis the Tiamat. By the time the ensuing battle was over three days, 4 hours and 15 minutes had passed, and only five of the original 30 Royal Guards were left alive.
By the end of the epic battle Luna had been stabbed and cut half a dozen times by magic blades designed to hurt and kill gods... the battle was one of the three longest Luna ever participated in... Luna finally destroyed Alexis by teleporting both of them onto the coast and summoning a giant tidal wave. The wave contained the combined kinetic and potential energy of every single wave that had ever existed, and this only knocked the witch out cold. Luna immediately followed up with a blast from the Elements of Harmony, the rainbow colored beam lifted up, encircled and crushed the unconscious witch to death. Then the ball-like covering contained the huge explosion that followed. Luna felt the thrill of battle for the first time but she also realized that bloodlust would inevitably lead to tragedy so she tried to restrain herself. With the aid of both powerful magic and the Elements themselves Luna was able to make sure that her enjoyment of battle did not get out of hand.
2nd, after she had recovered from her wounds Luna went to work. She had two separate layers of battle armor magically created and then transformed into a summonable form of liquid metal. The princes of the night also created a special outfit that had had once been made of 5 layers of clothing: the first was a comfort layer, than there was a layer of Hydra skin, in the middle a layer of Dragon scales, next was a layer of Hydra skin, and finally touching her own fur and skin was another comfort layer. With the aid of magical energy siphoned directly from the Heart of Ponyland the layers were compacted, stretched impossibly thin, and became one layer of clothing.
40 years later, the “Princess of Hiding Darkness” went into the Armory of Confiscated Weapons on the night after she and her sister’s first encounter (of many) with the Demon Ram known as Grogar the Greggur (meaning Grand-Necromancer), seeking an auxiliary weapon to use against those who were either sealed it from or immune to the Elements of Harmony. There she removed one elder blade and it’s scabbard from a wall-mounted a place of honor. The weapon was a magical sword taken from the first demon she had ever smited (it had already gone up in a rainbow implosion as did all dying demons). Thus Luna gained a sword made of wrought iron, she used this blade for one third of her career as a fiend slayer.
Nearly two centuries later the sword was destroyed in battle with a a very powerful black magic using goblin named Malcarge the Melter, who liked turning small buildings into lava with the occupants still inside, with the rights spell he could also shatter the bones of his victims while they were still alive. He had been tricked into reading on black magic spell by a demon and because black magic always extract a price from the spellcaster unless they are demon, the poor Troll (formerly called Dasnax-vab, the name meaning “Honorable Blacksmith”) was turned into a powerful spellcaster without empathy and assumed a misshapen appearance.
Three days later, Luna received a very unusual birthday present: a far more powerful magic sword composed mostly of wrought iron that had been blessed by every kind of priest and mystic teacher imaginable as well as by an entire Pantheon of deities (only one of whom was still active on the planet’s surface) with a special core of a marble-sized but still very powerful fragment of rainbow energy that was fired by the Elements of Harmony, and finally had been dipped in left over Ichor in order to make the sword all but indestructible. An unexpected side effect of the Ichor is that the sword will often change width during battle mostly at random, though there does seems to be a certain set limit as to how big the sword will get without its owner needing a particular size.
Although Princess Luna would have preferred a plainer scabbard (one more in keeping with her recently gained reputation as the Ponie’s Princess, due to her spending far more time with her subjects in public and in person because she enjoys socializing with them and could publicly be humbled by the powers she wielded) playing it was instead made of crystal, the kind that grew up around the Heart of Ponyland.
It was around this time that the arbitrator that pony land has long waited for arrived in the form of the “Ruler of All-Kingdoms”, Princess Tiffany Majesty. With the aid of her well-informed husband (Steve Aguanno) Princess Majesty serves as the final arbitrator, peacemaker, and negotiator for all issues that deal with at least three of the many small kingdoms that existed within Ponyland.
She has held court for many years in Her white palace named Dream Castle, and she is considered by Griffin historians to be slightly more powerful than Starswirl the Bearded in terms of raw power. For a little over 6000 years she was considered to be the most powerful unicorn alive, and she specializes in offensive and defensive elemental magic, preferring to use various kinds of lightning spells when lethal force is required.