Welcome to my first guide. In this guide I will explain how to play Diana mid and jungle and which runes, masteries and items to take. Before you downvote let me know in the comments why. Maybe i can change something in my guide.

An unyielding avatar of the moon's power, Diana wages a dark crusade against the sun-worshipping Solari. Though she once sought the acceptance of her people, years of futile struggle shaped her into a bitter, resentful warrior. She now presents her foes with a terrible ultimatum: revere the moon's light, or die by her crescent blade.

Though she was born to the Solari, Diana's inquisitive nature set her apart from her brethren. She had always found solace and guidance in the night sky, and questioned the dominance of the sun in her society. The Solari elders responded to her challenges with only derision and punishment. Diana remained convinced, however, that if she could find evidence of the moon's power, the elders would listen to reason. For years, she studied Solari archives in solitude until she discovered an encoded message hidden in an old tome. This clue led her to a secluded valley on Mount Targon where she unearthed the hidden entrance to an ancient, sealed temple. Inside, among aging relics and faded murals, she found an ornate suit of armor and a beautiful crescent blade, both inscribed with sigils of the moon. Diana donned the armaments and returned to the Solari elders that night. She declared that the artifacts proved others had once worshipped the moon as she did. Her discovery of evidence challenging Solari dominion shocked the elders. To Diana's horror, they pronounced her a heretic and condemned her to death. As the elders prepared her for execution, Diana's anger and sorrow overwhelmed her desire for acceptance. She lifted her gaze to the sky, calling upon the moon for strength. Lunar power surged within her and she shattered her bindings. Raising her relic blade, she turned and slaughtered the elders. With the temple in ruins behind her, Diana resolved to destroy all those who would deny the power of the moon.

''The sun does not reveal truth. Its light only burns and blinds.''
-- Diana

Pros:

-Strong Farmer/Pusher
-Can frequently deal high burst damage
-In my opinion even after nerf op

Cons:

-Heavily mana dependent
-Continued mobility relies on skillshot
-Has no escape tools

Diana swings her blade to unleash a bolt of lunar energy that deals damage in an arc before exploding. Afflicts enemies struck with the Moonlight debuff, revealing them.
Unleashes a bolt of lunar energy in an arc dealing 70/110/150/190/230 (+0.7) magic damage.

Afflicts enemies struck with Moonlight, revealing them for 3 seconds.

Cost
55 Mana
Range
830


Diana creates three orbiting spheres that detonate on contact with enemies to deal damage in an area. She also gains a temporary shield that absorbs damage. This shield is refreshed if her third sphere detonates.
Creates three orbiting spheres that explode on contact with enemies dealing 20/34/48/62/76 (+0.2) magic damage. Lasts 4 seconds.

Also gains a temporary shield that absorbs 55/80/105/130/155 (+0.45) damage. This shield is refreshed if the third sphere detonates.

Cost
60/70/80/90/100 Mana
Range
0


Diana draws in and slows all nearby enemies.
Draws in all nearby enemies and slows them by 35/40/45/50/55% for 2 seconds.

Cost
70 Mana
Range
450


Diana teleports to an enemy and deals magic damage. Lunar Rush has no cooldown when used to teleport to a target afflicted with Moonlight.
Becomes the living embodiment of the vengeful moon, teleporting to an enemy and dealing 100/160/220 (+0.6) magic damage.

Lunar Rush has no cooldown when used to teleport to an enemy afflicted with Moonlight.

Cost
50/65/80 Mana
Range
900


Gains Attack Speed. Every third strike cleaves nearby enemies for additional magic damage.

Mid runes:



For playing mid I recommend some magic penetration but mostly ability power, to deal as much damage as possible.

Jungle runes:



Jungle runes are a bit different from mid runes. I take attackspeed marks to use Diana's passive more often, what is important and makes jungling easier. I take armor seals to get more survibility. The ability power glyphs are for a higher damage and for quintessences i use magic penetration.

Mid:

21/0/9 using the 9 points to gain some mana and mana regeneration.

Jungle:

21/0/9 using the 9 points to get extra movement speed and increase the duration of buffs by 20%.
This is very important for jungling.

I Take these boots to get additional attackspeed. You need it for your passive, which gets very strong at mid/late game.

This is your most important item. You don't get much ability power but you get 50% additional attackspeed. This makes you able to use your passive all the time.

This is also an important item. As Diana you need a high survibility. So take it to get more HP. It also gives you a good amount of mana.

This is a good item for Diana because she is a melee caster and it lowers the magic resistence of nearby enemys. You also get much ability power.

I take this item to lower your enemys movement speed with your skills and also to get more HP, what is very important.

Finally I take Rabadon's Deathcap for a big amount of ability power.

It's not important if you go mid or jungle. You have to max Crescent Strike first because it's your main damage tool. Second you max Pale Cascade because it deals a good amount of damage and also gives you a good shield, which is important for jungling. 1 points in Moonfall at lvl 4 is enough. Max this skills last. You put a point in your ultimate at lvl 6, 11 and 16.

Take flash to escape or to get to your enemys. Take this spell in jungle and when you play mid.

Take this spell if you play mid. It's good for some extra damage.

Take Smite for jungling.

This is your jungling route:

1.wolves
2.blue buff
3.ghosts
4.golems
5.red buff

Tips:
1. Be sure that you position yourself so that your passive hits all monsters.
2. Attack with Crescent Strike first and use Pale Cascade when you are getting attacked by the monsters.
3. You can use Crescent Strike to make monsters visible and jump over walls to them with Lunar Rush

1. You should try to cast Lunar Rush only if you did hit Crescent Strike on your enemy.
2. If you want to attack use Crescent Strike and directly use Lunar Rush. Then you should use Pale Cascade to deal more damage and to gain more survibility. If your enemy tries to run use Moonfall or Lunar Rush again, which has no cooldown because you landed Crescent Strike before.

Here are some of my Diana stats. I know one of the games is lost but i took it because it has a nice score. In all of these games I used the build shown in this guide.

I hope I was able to help you with my guide. It's not the best because it's my first one, but i think it's ok. Please leave some critism and let me know if you would change or add something.