There's a number of League of Legends characters listed as charactername_(lol) where charactername isn't aliased to any character, one of which being Rengar, but when I suggest the alias, I get the message "Error: rengar is already aliased to something" yet when I search "rengar" I get the message "No posts matched your search." and the Rengar_(lol) wiki page shows that nothing is aliased to the tag.

I think you're getting that error because you've already submitted an alias suggestion for rengar: forum #203996

I agree the error message could be more helpful.

Maxpizzle said:
I think you're getting that error because you've already submitted an alias suggestion for rengar: forum #203996

I agree the error message could be more helpful.

Oh, weird, I forgot about that. That's kind of neat that it keeps track of that though.

It also does this with things that aren't implicated or aliased but other things are aliased to that.