Maybe take that bonus damage that you are giving to Kayn against monsters and let Nautilus have some

As fun as it is to run out of mana after 3 camps, it would sure be nice not to have to recall before finishing your clear when you are the slowest champion in the game.

Update: Oh Nautilus is just fine at his 44% win rate and his .75% play rate. Sorry to suggest something that would actually make him viable in a role and not just relegated to support because he's too weak to be played anywhere else now.