Now that I think of it, Diana may need a small nerf come 8.4.
And the reason being is this little bugger right here:
Now, Diana is a diver/assassin. Her job is to blow squishies up, and right now, she does this quite well. According to champion.gg, she's sitting at a respectable 51% win rate, with a 2% play rate. Absolutely by no means overpowered or underpowered, but quite healthy all around. Not to mention that she is extremely satisfying. Everything in her kit compliments each other just right.
My problem comes to her laning phase. Pre level 6, she can be abused and harassed very easily by anyone. She can return some of the harass, but she does have to keep a watchful eye over her mana, since in the early game, it can run out pretty quickly. Post level 6, however, she can win her lane right then and there, especially against immobile mages like Lux or TF (those two being my favorite matchups with her). This is all fine and dandy until you come to the more durable mid laners.
Take Vlad for example. He's by no means a counter to Diana, but also Diana can't really do anything to him. The lane essentially becomes a stale mate because Diana can't kill Vlad, and Vlad can't get close enough to Diana to really do anything to her. But come 8.4......this will all change. See, Diana currently builds 
as a first item. While her mana costs can hurt her in the lane phase, they aren't that bad to where she desperately needs the mana in order to function. So, she can safely go with a non-mana item in order to get her going. Against the likes of a Vlad, the new Morellonomicon will allow her to completely dominate the lane, since, you know, Vlad won't be able to heal anymore, and it will likely be before he gets any magic resist, thus increasing the amount of damage she will do to him. And the extra health on top plays in very nicely with Diana's playstyle, so, she would be able to endure any kind of damage that Vlad puts out.
But, it doesn't end there. Morellonomicon gives flat penetration, a stat that is best used against targets who have low defenses. Diana does sometimes build 
, but she would much rather be building raw damage, that way her targets simply go "poof!" The new Morellonomicon will give her the ability to burst champs down that she already performs very well against even better than now.......while still in the laning phase.
Now, you might be saying "But, Electro, doesn't Diana need the on hit damage and attack speed from Nashors?" As of right now, yes. However, she can get by without it. Her passive has enough damage in it to where she can work without the on hit damage, and her E gives her enough attack speed as well. Most of her damage comes from her Q, W, and R, all of which don't really need any kind of help dealing damage until later in the game, it's just that Nashor's Tooth, and Lich Bane help compliment the parts of her kit that do need the extra help.
Back before Diana got a few tweaks here and there (extra attack speed on passive, extra attack speed on E, rotation of orbs on W increased), people would build straight up raw damage on her......kind of like a mage. Nashor's Tooth was kind of a noob trap on her, and Lich Bane was only built to counter her mana costs. But now that her abilities do enough damage on their own, and her build is only meant to compliment the parts that do still need some help......I can certainly see a world where people gravitate towards a raw damage build again.......and Morellonomicon will likely be the first item they get.
So, here are my suggestions:
- Don't nerf Morellonomicon. I know that there are plenty of mages who need that item, and it's a good item.
- Increase the mana cost on Diana's Q by just a bit. Say like.......5 mana (55 to 60). This should make her a little more wary of how many times she uses her Q, and may push her a little more towards Sheen.
- Reduce the bonus attack speed she gets from E at early levels. Maybe go from (50/60/70/80/90%) to (35/50/65/80/95%). This would most likely keep her from building Morello's as a first item, and stick with Nashors.
- Increase the CD on her ult at rank 1, but reduce it at rank 3. Possibly go from (25/20/15) to (30/20/10). This would punish her more if she ends up using it without her Q, and give her targets more room to breathe. However, as compensation, you would take that time taken off, and put it on her rank 3 ultimate. Her late game has never been fantastic anyway, so, it could use a little love (in fact, I would recommend this change regardless of the new Morello's coming out)
Now, I am not saying to put through all 3 nerfs......that's probably too much. If anything, I would suggest just 1 or 2 of them. Diana is in a healthy spot right now, and I doubt the AP item pass will do much to change that. So, we shouldn't hit her too hard.
TL;DR
The new Morellonomicon may make Diana a bit too strong. I suggest nerfing her in 1 or 2 ways that i suggested above.
