"Me and a legendary witch" isn't proper English.
There's no such thing as proper English
This statement is an oxymoron. If it's true, it can't possibly mean anything concrete, because without proper English, there's no proper way to interpret it. But then if that were the case, I wouldn't be able to reason that to begin with because I never interpreted it in the first place.
I interpreted it, so it's wrong, and thus my statement stands. "Me and a legendary witch" isn't proper English.
I'm willing to bet you're just trying to be funny by pointing out that English has a lot of inconsistencies, and you're correct on that, but that doesn't mean we can't or shouldn't use it in the established way.