Harmony

History
Harmony was one of the seven ancient powers that created existence. like it's fellow powers, Harmony was passed down from its sorcerer Somania and it's been used by many heroes and protectors throughout history. the most well known users of this power were the pillars of Equestria, who used it to both battle evil and challenge Stygian when he was possessed by the Shadow. after them, the next users were Celestia and Luna, who used it to turn Discord into stone and Celestia later used it to banish Luna(Nightmare Moon) to the moon. the next users were the Mane Six and their human counterparts, who both use it to protect their homes. Tirek also wielded this power, but wasn't able to use its powers of order. the final user was Dante, who was able to use its full power right when he got it.

Purpose
not to be confused with Unity, Harmony's purpose is to maintain order and stability throughout the universes. it also has the power to choose who should possess it and can manifest as conduits like the tree of harmony or the castle of friendship with its map. it can also seal away threats it deems dangerous to the stability of the world.

Users
The Pillars: the power of Harmony, at some point, became fragmented and soon began endowing groups with its power. the first group was the pillars who used its power to ensure stability and goodness reigned over Equestria. Celestia and Luna: they found the tree along with the elements, which the Pillars planted a few hundred years before, and were endowed with the power of Harmony. they used this power to imprison Discord in stone Celestia, later on, used it to banish Luna to the moon.
 * Rockhoof: his piece of Harmony gave him immense strength and it seems as though this piece is the strong effect of Harmony over the universe.
 * Mage Meadowbrook: she seems to possess the compassionate piece of Harmony and it gives her great knowledge of potions and the ability to heal any affliction,
 * Flash Magnus: he seems to possess the calming piece of Harmony, which gives him great courage and tactical genius.
 * Mistmane: she seems to possess the purifying piece of Harmony, which allows her to restore things to its natural image.
 * Somnambula: she seems to possess the belief piece of Harmony, which gives her the ability to face any danger with hope and the belief that things will be okay.
 * Star Swirl: he seems to possess the knowledge piece of Harmony, which gives him the power of great magic and the ability to create spells.

The Mane Six: after they found the elements( and probably when they were born) the power of Harmony chose them as its new users. together, they are able to summon a rainbow blast that can both destroy or imprison a target, but separately, they can manifest even greater power. The Humane Six: after they found the crystal pieces, Harmony fragmented even more and chose them as users too. they are able to manifest powers that resemble actual superpowers and can also preform the rainbow blast. Tirek: after Discord captured them, Tirek stole the power of Harmony from the group and the final piece from Twilight, and he didn't manifest the stabilizing effect or the rainbow blast. he did gain enough power to break free from his wrist cuffs.
 * Applejack: she inherited the strong piece of Harmony and it endows her with great strength, but later she manifests the ability to control rock and the element of earth.
 * Rainbow Dash: she inherited the lingering piece of Harmony, which gives her great speed and courage. she later on manifests the ability to control weather and summon storms from thin air.
 * Rarity: she inherited the giving piece of Harmony, which gives here great creative genius and a keen eye for details. she later on manifests the ability to control water and can even create shapes from ice.
 * Fluttershy: she inherited the compassionate piece of Harmony, which gives her great sense of love and the ability to see the best in people. despite having immense fear, she manifests the ability to shapeshift into whatever she can imagine.
 * Pinkie Pie: she inherited the fun piece of Harmony, which gives her a great sense of humor and the ability to be blissfully ignorant of danger. even though she hardly ever takes a threat seriously, she manifests the power to create powerful illusions from here huge imagination.
 * Twilight Sparkle: she inherited the knowledge piece of Harmony, which giver her great mental ability and magic proficiency. she later manifests the power to predict what someone will do next and extreme magical power growth.
 * Humane Fluttershy: at first, she possesses the ability to talk to animals(like her equine counterpart), but she is the first to unlock and even greater form of her powers. she gains the ability to summon magically enhanced versions of animal powers, which allows her to fight Dante equally.
 * Humane Applejack: she first has the power of super strength, but she is the second to unlock her greater power. after Dante is about to preform a spell that could beat Fluttershy, she gain the power to turn her skin into organic steel, which exponentially increases her durability and strength.
 * Humane Rarity: she has the power to create diamond plates, but she's the third to manifest her greater power. after Dante begin over whelming the powerhouse duo, she gained the power to create diamond hard objects from thin air(similar to Rarity when she was in the comic world). she uses this power to create a suit of armor along with a katana and she seems to gain extreme weapon proficiency.
 * Humane Pinkie Pie: she has the power to make sugary treats explode, but she's the fourth one to manifest greater power. after Dante is still able to hold his own against the three, she manifests the ability to create pure explosions, which she can release like a machine gun or place them in her limbs and deliver explosive punches or kicks.
 * Humane Rainbow Dash: she has the power of super speed(much like equine Pinkie in the comic world), but she's the fifth one to manifest greater power. after Dante tries to flee from the strong team, she manifests the ability to run so fast it looks like she's teleporting. she also can generate electricity and discharge it at a target.
 * Humane Twilight Sparkle: she has the power of telekinesis(much like every unicorn in Equestria), but she's the sixth one to manifest greater power. after Dante is able to escape the other five, she manifests the ability to not only gain even stronger mental power, but can also use magic that's a fraction of equine Twilight's power.
 * Sunset: she has the power to see inside another person's mind, but she's the last one to manifest greater power. she manifests the ability to read people's minds and preform astral projection, but she keeps this secret until Dante flings himself and the Shadow into Limbo.

Dante: after Dante defeated equine Twilight in rage mode, he finally took the full power of Harmony and was able to use its power right off the bat. he soon became a member of the Mane Six and wielded his own version of Harmony, which he figured was the healing piece. before he destroyed his element, and lost his connection to Harmony, Dante trained the heroes and taught them how to master their newfound abilities.