“Cataclysm Eve is based on the protagonist of the fanfic ’Friendship is Mind Control’, a Twilight that became seduced by the power of controlling others, and finally became the Princess of Magic. Imagining what might happen if she gave in to all of her worst, most selfish impulses – becoming corrupt in mind and body, like Nightmare Moon, or Daybreaker – Cataclysm Eve is a living tornado of magical power, seeking out and seizing sources of magic, and transforming her friends and enemies both into her fawning puppets.”
Additionally, there are like fifty kabajalillion interpretations of Nightmare Twilight before FG was even revealed. :3
That’s Sci-Twi’s. Also, this is a dark form based on Twilight’s personality in a fanfic so there’s bound to be differences