Thanks for the guide review!

Thy sins
1. No C2V
2. Do not get AP on marks, it doesnt work well.
3. Neither does that skill order.
4. No summoner spell explanations
5. Loads of oneline explanations
6. Well, just lacking a lot of explanations really

Thy blessing
1. Cheatsheet structure seems decent enough
2. Good use of structure

Result: Path of Redemption
There is not much positive I can say about your guide I am afraid. In order to make it a legit guide you will have to rework a lot. First of all, make a full build explanation, fix your build and stuff. Make sure you read some of the links given here, so your guide can vastly improve.

Good luck

(Do not forget to vote! :D)

Greater Mark of Scaling Ability Power in my opinion give you an edge early game to get fed. Sometimes, that last ditch of damage really does it.

I will consider the mastery change, because I see that Double-Edged Sword would be much more useful!

I would rather max Crescent Strike and Pale Cascade at the same time for surviving while diving. Plus the more damage the shield can take is extremely helpful, while your Q enables you to jump in and do the most damage from, R, W, and then re-Q and R. I believe it is necessary to max both.

I feel like Greater Mark of Scaling Ability Power aren't worth at all, only 0.1 per level isn't enough. Why those over the traditional MPen ?
In your masteries, since Diana is a melee, I'd take Double-Edged Sword over that lonely point in Fury .
And why maxing both q and w at the same time ? Not q first ?