Diana

Middle

Embrace the Night

Burst damage and maximum assassination.

Domination

Burst damage and target access

Electrocute

Hitting a champion with 3 separate attacks or abilities in 2s deals bonus adaptive damage.
Sudden Impact

Gain a burst of Lethality and Magic Penetration after using a dash, leap, blink, teleport, or on leaving stealth.
Eyeball Collection

Collect eyeballs for champion and ward takedowns. Gain permanent AD or AP, Adaptive for each eyeball plus bonus upon collection completion.
Relentless Hunter

Unique champion takedowns grant permanent out of combat MS.

Sorcery

Empowered abilities and resource manipulation

Absolute Focus

While above 70% health, gain up to +40 Ability Power or +28 Attack Damage (based on level), Adaptive.
Scorch

Your first ability hit every 20s burns champions.

Offense

+9% Attack Speed
Flex

+6 AD or 10 AP
Defense

+5 Armor or 6 MR (match-up)

WhyElectrocute

As a champion with a very assassin heavy play style, Diana loves the burst from Electrocute. She can proc the damage pre 6 with an [E]->[W]->auto thanks to the spells not having to do damage to count toward the proc.

WhySudden Impact

Post 6 Sudden impact because a vital tool in blowing up enemy champions with all-ins.

WhyEyeball Collection

Diana's assassin playstyle makes her heavily reliant on picking up quick kills and snowballing a lead and Eyeball Collection does just that.

WhyRelentless Hunter

Relentless Hunter is a bit of a stylistic choice. As an assassin, Diana usually wants to type to roam a bit and find a target to explode.

WhyAbsolute Focus

As as Assassin your damage pattern will typically consist of bursting someone 100 to 0 at the start of a fight, meaning you should remain above the threshold for Absolute Focus for the entirety of your rotation.

WhyScorch

Scorch is a rune that heavily focuses early to mid game chip damage. If you're confident in your ability to land [Q] often is lane this can potentially put you in a great position to kill your lane opponent at 6.