Flash Magnus was a lowly cadet within the Royal Legion of Cloudsdale, under instruction of Commander Ironhead. During one flight, he and his troop had to go through the Dragon Lands to reach their comrades on the otherside. During the flight, he was ambushed by Torch and his mate. He managed to escape, but found two of his comrades captured. He was about to fly in to save them when Ironhead stopped him, and brought him back to the troops. He tried to get his troops to save his comrades, but was told by Ironhead that it was an impossible task, and that nothing could work. Flash Magnus then came up with a plan to outfly the dragons in an attempt to lure Torch out so the others could rescue the comrades. He was given Netitus for the task by Ironhead, and he went in to lure the dragons away. He flew just fast enough to avoid many of the attacks, and only managed to fully escape when luring Torch and his mate into a storm cloud. As described by Rainbow Dash, he returned from the Dragon Lands as the bravest Pegasus in Cloudsdale.
He returns to present day after the Harmony Gems bring them back, and she joins the others in fighting the Pony of shadows to put him back into Limbo.
It is revealed that he became captain of Canterlot's royal guard not long after this.
My Little Universe II
She briefly appears as part of the Pillars during the three-part finale, fighting Grogar's Army in the Realm of Corners. He was volunteered to play out the final plan during the third part, but is stopped and replaced by Discord.