Just about anything I've ever come up with Anime or a superhero comic got to first, except for this one idea from long ago...
I once came up with this idea for a "Sword Mage" - somebody who can extend the sharp edge of a sword long beyond the actual length of the sword (so imagine somebody swinging a three foot long sword at a person 100 feet away and chopping them in half - that sort of thing).
I did use it in Re:Apotheosis to a small degree - Daiki Yamato's sword can do that, but you don't actually get to see it until the sequel goes live in December.
That said, one of the new characters in the sequel, Aquila, can read other people's character descriptions. So, if she showed up in somebody else's story, she could just look at a character and read what their author wrote, including all of the notes. She can also erase a character from their own story. ...let's just say you don't want to get on her bad side.