After the results show, Nocturne was 2nd to last on the poll and might be the last champion to get his rework of the 5, but that doesn't mean he shouldn't be talked about, and this gives us plenty of time to think of some ideas for the nightmare. Since Nocturne is suppose to be a living nightmare and kills his victims with fear, that's what his kit and his lore should be revolved around.
But what do people fear, spiders, the dark, clowns, losing your promos, death? Everyone fears something, it's always different and sometimes we don't know what that fear is, but there is one fear everyone that not even the most courageous can handle.
The unknown. Not knowing on what could happen and fear on what that outcome could be, is scarier than knowing what will happen next. That's what Nocturne does, he brings fear to the ones that don't understand, Every region of Runeterra fears something that wish not to handle and would rather lock it away or isolate it from the outside world hoping history will forget.
So instead of being this shadow demon with blades he uses to kill his victims with, he's more of a well... thing. He's still looks like a shadow but with the blades removed, or at least the metal part is, and instead he can uses his body to transform into anything while still having that dark shadow look, such as the blades he uses to kill people with. Or maybe even using his transforming powers till kill people with.
And so he lurks behind the victim, and the victim feels his presences but they don't see him. Longer and longer Nocturne sticks to them, the more insane they become, they would sometimes see illusions of multiple shadow figures around them. And without knowing who the victim attacks, they would kill their own love ones, and destroy everything they build. Sometimes Nocturne doesn't kill his victims, but lets them destroy themselves from the inside. And makes you wonder is he even real, or just a figment of our imagination?
So how would this work for his gameplay? I only have one idea and it's for his ultimate. I love it and was the first ultimate I liked when coming into LoL, but sadly would have to change into some sort of an illusion ultimate, where his player models would show to the poor sucker he cast it on, and the illusion would either be made up of their teammates which the player could attack and team kill their allies, or just fake copies of Nocturne and for each fake copy destroyed would hurt the player.
He should also rely more on the fear effect since he suppose to be a living nightmare, not some bladed creature that couldn't get into the band Pentakill.
This is something I just came up with in one day, and some of it did sounded better in my head. But it's something to think about, and you guys can make changes or say this should be this instead. But I think it should relate to how the fear of the unknown destroy someone from the inside and even civilizations.