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^ That's not what Tomato in the Mirror means; that trope is about a character's identity, not about using mirrors or reflections as weapons.
This is more like Achilles' Heel, that Sybil's one weakness that defeats her is specifically her own reflection and nothing else (just like how Achilles' one weakness was his vulnerable heel).
Mirrors Reflect Everything explicitely excludes examples that simply show back an image. If however the ugliness is supernatural to a degree, that it is harmful to anyone seeing it, it might still fit in there.
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In Welcome to the Wicked Wax Museum (give yourself Goosebumps), Sybil (the villain) couldn't bear to look at herself in the mirror shown by the protagonist and melt. In Crazy Haunted House (an old Inkagames/Mazniac game), the main character has to show mirror to a head monster to defeat it https://www.youtube.com/watch?v=t75JWOIjArY
(4:53). Is there a trope for this?
Edited by LucasdaKool