Twilight Sparkle: "Oh, she's fine now, because erasing also retroactively erases what did to Fluttershy, along with all traces of 's existence. She only know that she was being hurt by because I told her so."
Princess Luna "Thou seems to take thy action of erasing somepony from existence too casually for comfort..."
Princess Celestia: "I'm afraid you're mistaken, sister. The Shcrödinger Invocation does more than simply...'delete' the target from reality. Am I correct, Twilight?"
Twilight Sparkle: *blinks* "Of...course, Princess. But I stand by it, ___ deserved what he--"
Princess Celestia: "Twilight Sparkle...do you *truly* know what that spell does to it's target? The exact arcane-scientific details?" (levels a slight glare at Twilight)
Twilight Sparkle: "It--it's based off of theories of applied quantum physics, especially Schrödinger's Cat, and--" (cuts herself off as realization finally dawns) "--No, that can't be it. I just erased __, __ is just gone; I didn't do THAT..."
Princess Luna: "Shcrödinger's Cat...doth thou mean that ridiculous theory about all possibilities occurring at once? What use could such hokum have for spells? ...Sister, tell us that spell *didn't* do what we think it did. Tell me the name is but a choice of fancy...!"
Princess Celestia: "No, Luna. The name has meaning. That spell warps probability and alternity for the target. All possibilities, all alternates, every single May Have Been, Never-Should, and Here and Now become the target's reality--all at once. They both everywhere, and nowhere; alive and dead; real and imagined...all at the same time. And the contradictions between these alternates, the opposites? They cancel each other out, one after the other, until..."
Twilight Sparkle: (she's been crying for a while now--she wipes away tears from reddened eyes as she speaks up) "Until...*sniff*...until their reality; their very BEING...just degenerates into a mass of imaginary numbers and formless atoms. The spell takes seconds, but the target experiences a trillion billion different lifetimes and universes, and EVERY...possible... variant of each and every one--all at once. They just get...torn between infinity...what have I done? WHAT HAVE I DONE?!?" (Breaks down crying)