Diana has a bit too much of everything
I appreciate Diana's design and even the thought that went into her rework, but I think that some of her numbers are just too high, and it makes her really good at too many things.
First of all, she's really bulky for the very little amount of bulk she builds, which is usually just one AP/HP item like protobelt or ROA. She has very strong burst in all stages of the game and is especially stronger in the early game since her dash is on her E, which essentially gets rid of her past pre-6 weakness. She also has very good duelling and sustained damage with her passive.
Now, none of these things on their own are a big problem; every champion is entitled to their strengths and weaknesses. However, I feel like Diana holds the upsides of both being an Assasin and a bruiser without many of the downsides. She's able to OHKO carries but is capable of taking large amounts of damage while having sustained damage.
I have some suggestions:
I really like how Diana is an Assasin-bruiser hybrid, but I think she's got a bit too much assassination potential, and I'd like to see her move towards more prolonged fighting.
Maybe lower the AP ratio of her dash to 25% instead of 40%? It doesn't make a ton of sense to me why her dash should be dealing that much damage. In compensation though, maybe increase the base damage of her W balls, and make the shield that she gets upon striking the last ball extra fat to encourage longer fights. Maybe her Q could stand to lose some AP scaling as well, but I'm not sure.
Either way, I don't think Diana is THAT busted, and I don't despise how she is currently, but I think she's a bit too good at too many things. Let me know what you think though!