Beware, everything below is according to legends and rumors and may not all be true:
Ascending Phoenix, otherwise known as Phoenix is a Pegasus pony. She is over 120 years old and shows no signs of aging because of the magic imbued in her. Phoenix comes from a far away land called Epscillar. She was born as a normal blue and white Pegasus. But was later taken into a secret program for magic testing at the age of 4. The compound she was prisoned in held many insane and ambitious wizards. Subjects there were subjected to extreme amounts of magic. Phoenix was targeted by imbuing spells that resulted in a phoenix, dragon, and leviathan’s magic being imbued within her. One day, she was secretly taken into a lab room with one of the crazier wizards. He tried to imbue her with greater phoenix magic that has ever been applied to a pony. Luckily, his colleagues heard the ringing of the magic and stopped him from destroying her. But she had not escaped without a scar. Her right eye was altered, so she can now see hidden magic waves and can perceive movements faster. She was held captive there until she was 17 years old. After learning that she was made to be a weapon of war, she broke free of her captors and escaped. For 13 years, she has been wandering the lands with her captors at her heels, trying to catch her. Throughout this time, she was constantly attacked by her captor’s cursed crystals. She has suffered many wounds because of those crystals. On one day, she took a close look at the crystal with her right eye. She noticed that the crystal had a very dark aura to it. Phoenix tried many spells with her magical abilities to destroy the crystal but it stayed intact. During that night, the crystal seemed to whisper to her, and Phoenix crept closer as she was intrigued. The dark magic suddenly surged upwards towards her. She could not dodge at such a close range and was instantly hit. The dark crystal magic gave her a crystal shield 0n her hooves. They also gave her the ability to summon crystals to attack or defend. But it drained her magic slowly and constantly when she summoned those crystals. And she felt stabbing pain from them once in a while. She later escaped into a town called Fraye. Phoenix thought she was safe there, but was attacked by 20 magic wielding ponies later that week. They ambushed her when she exited her cave located next to the town. They trapped her in a shell of dark crystal, but she shattered it with her newfound crystal magic. She then blew flame at 3 wizards before they had the time to react. The rest blocked her flame breath with magic shields. They then launched magic laser beams at her. She deflected by summoning a water shield that absorbed most of the energy. With an impossible speed, she flew up and dove at one of the wizards. Her wings blazed into fire and she slammed into him, sending him flying across the forest. The remaining 16 wizards turned around in astonishment. They tried to freeze her with a spell but they could not aim accurately enough because of her speed. One by one, they were taken out by the red and blue blaze until there were only 3 left. They all teleported away and escaped. Enraged, Phoenix launched a huge magical fireball at her cave and shattered the rocks and sent boulders flying. By the time she had calmed down, the town ponies had gathered around her. She apologized under their hateful and fearful gaze. Phoenix then left that town and journeyed around for 65 years. She was constantly attacked or ponies were constantly attempting to enslave her. Then she finally found peace in Ponyville. Although ponies were fearful of her bewildered appearance when she arrived, they grew to be more easy around her. She tries to be nice but is periodically haunted by the horrors that she has experienced. Today, she tries to hide her magically enhanced speed and powers to keep ponies from fearing her. Phoenix has befriended Rainbow Dash. She always let Rainbow win the races she has with her. Through Rainbow, she was introduced to the rest of the Mane 6.