Hello everyone,
This is my first build guide here on mobafire so please share any feedback you have. I will try to be as clear and concise as possible while still going for understandability by both experienced players and new ones. I play jungle pretty often and i have felt very strong as diana with these builds. I hope you like them.

+ Diana is a strong jungler who does not have to back until you choose you should buy items, if you are able to make use of scuttle crabs for additional lifesteal.
+ Diana is generally underestimated in the games that i have played her in, mostly because she doesn't have the same kind of presence that a shyvana would give off, but her damage and survivability can be on par with big threats like yasuo.
+ The Two-Three builds i've shared offer you versatility in your role as a jungler to either be a burst mage, an up-close fighter, or a fighter off-tank. Which you choose should always cater to your team's needs. If you have a lux and a leblanc, do not go burst mage.

- Diana is not a viable ganker until level 6, her ultimate is her only form of initiation unless she is able to walk directly up to the enemy.
- Diana is somewhat vulnerable to counter jungling since she is not capable of fighting enemies off one on one in the early game. Items are vital to her damage since her leveling does not increase damage drastically.

Passive: Moonsilver Blade
Diana's passive is an on-hit effect that procs on every 3rd attack. It deals bonus magic damage in a wide but short cone in front of you. If not used in a few seconds it will reset and you will have to build up to the 3rd attack again. The animation for this proc being ready is that your entire champion will glow a bright white until you make the attack, which will have a sweeping white animation to it. The damage of this proc does scale with your ability power.
-It makes your jungling very easy since you can damage every creep with some of your auto attacks
-This passive is the main reason that devourer Diana is an efficient choice. As a burst mage, you wont get much out of the passive once you hit mid-late game.

Q: Crescent Strike
This ability is a ranged skill shot that travels in a horizontal arc along the terrain. It passes through obstructions, minions, and champions and will not stop until it reaches its end marker or until it is deflected by something such as Wind Wall. All enemy champions and minions in the affected area will take the full damage regardless of how many are hit. The animation is hard to see which also makes it hard for enemies to dodge, however it is clear when enemies are hit by it because the ability also marks the target with a moonlight array coming out the top of them. This mark means that your ultimate can be used on them to consume the mark and reset your ultimate cooldown. The mark also grants vision of the enemies hit. The mark lasts several seconds, and the ultimate reset occurs instantly upon the completion of the dash.
-The arc motion that it is forces to go in is hard for enemies to predict, but also makes the ability hard to land. Sometimes it is more reliable at close range since it is sent out instantly.
-The speed of this skillshot is not too slow but I wouldn't consider it a fast one either. It feels like the speed is somewhere near a lux root.
-The marking effect works on all types of enemies so feel free to use that to speed up your jungling or taking dragon.

W: Pale Cascade
This ability is an activation that conjures three orbs that circle your champion at extremely close range. Upon activation you are shielded for an amount of damage dependant upon your leveling of this ability, if all three orbs make contact with an enemy minion or champion you will gain another shield for (i think) the same amount of damage that you initially received therefore doubling your shield. The orbs disappear upon contact. The activation and conditional shields do stack. The damage dealt by the orbs does.
-The orbs do considerable damage which makes them great for your jungling, especially since using them all grants you an additional shield. A single cast of this ability can wipe the three lesser raptors in a second or less at the ability's second or third level.
-Essential for initation, and should almost always be used in conjunction with your ultimate to maximize both damage and survivability.

E: Moonfall
This ability is a non-damaging, aoe that pulls every type of enemy toward its center, and subsequently slows enemies directly after for a short time. The draw-in is not strong enough to bring an enemy on the edge of the aoe to its center, but will bring them to if not very close to your attack range. The slow scales as you level the ability. This ability can cancel dashes and jumps including some i've witnessed are yasuo's dash and Vi's charge attack. The ability has about half a second of delay before the draw in is executed. There is a visible insignia that shows up in the aoe just before it, and during the execution the insignia lights up in the same color as your passive or Q abilities.
-This ability is vital to the fighter and off-tank roles, but much less so to the burst mage. The draw in and slow both will help you land more attacks on the enemies, cast your abilities with less miss chance, and also group up the enemy for team work plays if you have a malphite or a lux. The clustering of your enemies is extremely beneficial to your passive since it hits in a cone, your q can also be used efficiently here.
-The timing to cancel jumps and dashes is difficult, and will likely be more of luck rather than skill. It still wouldnt hurt to wait until after a dash for you to dash in yourself and use this ability knowing they have no further escapes.

R: Lunar Rush
Diana's ultimate lunar rush is a single target ability that dashes through that target ending up on the opposite side of them. If the target has been marked by her Q, lunar rush will have its cooldown reset upon its finish by consuming that mark. The dash itself executes quickly, faster than Vi's ultimate, but only slightly slower than Warwick's. To my knowledge it can be interrupted.
-This ability is vital to any role she plays as it is a source of great burst damage, but also a matter of positioning. The possibility of having it's cooldown reset means you can easily use it twice on the same enemy in quick succession for a swift assassination.
-A more advanced way to use this ability would be to use it on any marked enemy close to your target who is out of range, then use it again on your actual target. This very quickly closes the gap but is much more predictable and likely to be punished.
-Don't be afraid to use this to secure a kill even if you don't have the cooldown reset available. This ability is not meant to be an escape, although it can be if youre on the "wrong" side of the minions or can jump to a jungle creep. Remember your q gives vision so you can wall dash with this if you hit something.

As a jungler, Diana should always start her W. Then get Q for more damage to jungle creeps, level W or Q again, and then level E if you think you can get an early gank, or want to take a scuttle more quickly. If you are going with an off tank role, or the fighter role, you mainly want to level your W and E respectively. Feel free to leave Q in the dust as you will only need it for your ultimate proc.

For Burst Mage Diana, however, leveling Q as often as possible is essential as it is your only ranged ability, and your only means of harass.

For any build you are going to level your ultimate as often as possible.