Appearance, Personality and Powers
Gusty was a unicorn with a curvaceous horn and a long flowing mane and tail. Her cutie mark consists of leaves blowing in the wind.
Gusty was a quite brave as she stood up to Grogar, who was a powerful and terrifying tyrant at the time, alongside some other unicorns. She was also cunning as she came up with a plan to take Grogar's source of power away from him. However, considering that this was long before Equestria was established, she may have had some prejudice against pegasi and earth ponies, since her team consisted only of unicorns.
As a unicorn, Gusty was able to use magic with her horn, but the extent of her magic was unknown. Considering her cutie-mark, she was likely adept at using wind magic.
Thousands of years ago, long before the pony tribes united as one, the country that would be known as Equestria was a dark and forboding land where horrible monsters created by the evil emperor Grogar terrorized the populace so that they could fuel their creator's power with the denizens' fear. But then a brave unicorn named Gusty the Great rose up alongside her Unicorn Warriors to challenge his rule.
They encountered the evil ram atop the hill that would lead to Cloudsdale; The Unicorn Warriors shot magical beams into the clouds and wrapped around Grogar and pulled him to the ground, but the evil goat manages to break through the bonds as fear gave him power. The rest of the battle was unknown, but it was confirmed that she managed to steal away the Bewitching Bell, which was the source of Grogar's power, and banished him from the land.
Afterwards, Gusty hid the bell within an enchanted cave atop Mount Everhoof, which was protected by a powerful forcefield and magical winds to prevent anycreature from getting to it.
The story of Gusty's triumph over Grogar was told for generations, lasting over thousands of years. Princess Twilight Sparkle was seen telling the story to some sick foals in Ponyville Hospital.
Unfortunately, her victory was but a temporary solution, as after many millenia of waiting, Grogar returned to Equestria to enact his revenge on pony-kind. He also gathered the most sinister villains in the kingdom, who eventually retrieved his bell for him.