And Discord's just laughing in the background.

Though, it is kind of crazy how she's been able to create a spell that nearly matches Discord's own magic. Her Equal-Marks thing is essentially him "Discording" the Mane 6. It's just not as easily done and takes a little while to take effect. When you think about it, she might be more powerful magically than Twilight.

Though, Twilight clearly has the better potential to learn at a much faster rate. Considering their age difference. I suppose it'd kind of be like a Goku/Vegeta rivalry…

Oh my god! Majin Starlight Glimmer would be so cool!

She's still rather far from Discord, considering that as far as we know, stealing cutie marks is the only advanced spell she knows, while Discord is practically omnipotent.
Then again, we never truly learned why she stole those cutie marks. She only said she does it for equality and shit, but it was implied that's there's more to it.
And considering that stealing cutie marks is how Tirek gained his power…