Loyal Defender

I'm thinking there could be a powerful Unicorn villain named Mirage, who always had a fascination with creating magical hallucinations to dazzle ponies. Now, she's not an Anti-Trixie, for two main reasons. She's not really into being a magician, and she doesn't brag. But she DOES have some tricks up her sleeve. As a filly, she would have studied differing gases to create different hallucinations. However, after one show went wrong when her hallicunatory gases backfired, causing the crowd to see hallucinations for days afterward, she was forced to either leave town with her hallucination gases, or throw out her props and live a normal life. So she chose to abandon her town and pursue her own path. This road ultimately led her to study differing gases, but after a freak accident with her horn, a potion, and a loose can nozzle, she wound up gaining the ultimate ability to create more than hallucinations. She could create entire mirages, and inflict them onto ponies. Mirages so powerful, they practically blocked out the real world, making it seem as though the pony was in an entirely different world, yet the same at the same time.


Now, here's the bit that's still a work in progress - a side effect of using her mirage powers was that each time she did, she began to go insane, leading her to want to rule the world, in a world where everything appeared perfect, though all in a mirage, while everyone under her rule was under the effects of her mirage magic.