To start off I would like to say hello, Secondly I would like to say that this is my first build I am putting on here, So tips and positive feedback would be appreciated.

In this build I will try to cover Diana's true power as an AP Carry (Mid).
Although she can be used as a successful jungle I prefer using her in the Middle lane.

The runes I have set on here and use in game are just basic Ap Carry runes;
Magic Penetration Marks x9
Flat Mana Regen Seals x9
Flat Ability Power Glyphs x9
and
Flat Ability Power Quintessences x3

Diana has some but not a lot of base damage so the Magic Pen. helps Utilize her ability power.

She is an Ap carry which means she will burn through a lot of mana, this is why I use mana regen seals. ( I use flat mana regen because it helps early game, late game it doesnt matter because the mana needed will not be burned as quickly seeing as how you passively gain mana)

And then the Ability Power runes are there to help add some extra damage in the laneing phase.