I'll keep this guide simple and straigth. No useless and endless explanations. You can ask questions in comments though.

This is a BRUISER DIANA BUILD. This build will allow you to soak a ton of damage and to deal a ton of damage too. It won't give you tons of pentakills (I'm sure you can find AP Guides for that), but it sure will make you win teamfight at every ELO.

I personnaly prefer to play her in the jungle, but you can easily go on any lane with her.

Just remember that there is 3 core items.



These 3 items give you enough AP, magic penetration and CDR to carry all the game, while still giving you enough armor and magic resist to survive the teamfights.

After these 3 items, you can buy basically anything you want.

But I suggest you buy this :



This will give you the midgame damage you need, with magic resist and movement speed, two very important stats.

Then, depending on the game, you will build one of these 3 items :



I strongly suggest that you build Force of Nature on most games, as this item was made for Diana. You NEED this movement speed, you NEED more magic resist ; and most of all, you really need these 80 health regen that scale well with your shield and will give you the regeneration mechanism you lack.

However, if you think some strong armor is needed on top of the magic, resist, the Guardian Angel is perfect.

And if there is definitively no magic damage on your game, but tons of scary AD, then build a Randuin.

You will finish your build with a late game item. You will rarely make this item, but if you are fed (and you will often be), it will allow you to destroy the game once you have it. On top of being unkillable, you will also be deadly.