Madara Problem
The Madara Problem is when a writer creates a character so powerful that they can’t be beaten, and the writer has to either weaken them (which is a total bummer) or kill them with a ridiculous cheat move that makes no sense.
I had to kill my character with a magic sword from a random wizard who showed up late.
My villain was too strong, so I had to make him die from a banana peel.
I had to kill the strongest guy in my story with a single punch from a guy who didn’t even show up until the final chapter.