Cthulhu alone isnt enough, when i say def downs covered, i mean 50% def cap with himes alone, not with ambush/snipe.
That's why I said SSR Nike is a major bonus. But even then, there's hime that aren't SSR that come with stat reduction debuffs. Cthulu just puts the nail in the coffin that you can hit the cap, granted you pulled the right hime