I am Italian, I do not speak English very well ... You can like it or not this guide will be translated from English ... This is because I really feel can recommend a guide a bit 'different from usual, for Diana. After trying different builds, including the much-loved by all full ap, with a bit of ad, neglecting it may hurt more than 1.5 or attack speed or a nice 431 movement speed ... Without neglecting other features. I love this summoner and does much more harm than you can imagine and fear ... Happy reading and good game!

We start talking about the runes.
For my building and any other building in my opinion for serious diana is essential to choose the
Greater Quintessence of Ability Power
otherwise, as we provide you the much-loved first blood? There would be other methods, such as the exchange of Greater Glyph of Magic Resist with the Greater Glyph of Ability Power but I prefer to have more defense (probably unexpected by our opponents)...
You can still feel like you are better, more ability power is always handy, but beware attacks from a distance of some summoner as Caitlyn Morgana Lux etc.. which have a long range with their skills
Greater Mark of Attack Speed: I think this is the key to my building, you will have no attack speed needed to kill minions, towers and why not go ahead with the construction even your enemies summoner... For my building is essential have it.
Greater Seal Of Resilence: it's the key! defense against physical attacks is the first thing you have to worry about, and I think that you know it ... Otherwise you will be dead before they pull the w Pale Cascade and Flash

Well, here the question becomes more complex ... We start from the principle from which, according to my build, immediately after completing Mercury's Treads or Boots of Swiftness and Negatron Cloak, depending on the construction choice, you should take immediately the Zeal... This will allow you to get in the first two buildings a movement speed of 410, the third 430 approximately. is essential to have a good movement speed because Diana has no real way to escape... But also in attack mode, your enemies will have little chance of escape, given that most of them build a speed of 390. Seeing is believing ... And what satisfaction!
Playing with Diana I noticed that also have 500 ability power did not correspond to an actual domain of the lane, top mid or bot, but often there were more of those times that I was dead I could kill ... That's why I decided to focus less sull'ability power to give space to armor, attack speed and movement. On this reasoning, I have decided that it is essential to start with these objects:
Mercury's Treads Randuin's Omen Trinity Force Nashor's Tooth
This will give us all the bonuses we need to be competitive with Diana, then depending on how the game goes, dedicate all'ability power and / or damage all'attack, choosing between
Hextech Gunblade Abyssal Mask Rabadon's Deathcap Rylai's Crystal Scepter
Keep in mind that for the start of construction I had to let go of the increased mana, to focus on what I think is more useful, so use it sparingly!
The third building is the one I like best, I suggest you try it because it is amazing.
If your enemies do not attack too in a group you can put aside for a moment the idea of ending Randuin's Omen and focus on objects of attack.
I beg you, do not have to die! Not in the early levels, better kill in less than a death in the most ... Rather than wait for the liv 6, in the early stages with weakened Crescent Strike, and then finish with the combo q-r-w-e-r (at your discretion), because this construction is slow to start, especially the first two, and then you need time to be effective.I assure you that once inside view of my building, you can not do without certain items that until now you had not tried to Diana. Seeing is believing!!