INTRO
In Riot's eyes, Diana should be a diver and these changes are trying to push her even more in that direction. She's really the only one in that role who you can play in the mid lane (all other lack AOE) and I wish she'd stay there even after these changes.
Stat changes aren't considered here.
IMPORTANT: If you want to compare these changes to the live values here's a link to the wiki containing all the data you need: http://leagueoflegends.wikia.com/wiki/Diana.
ABILITIES
P - MOONSILVER BLADE
CLEAVE: After casting an ability Diana's next 3 auto-attacks in the next 3 seconds deal damage equal to 100% of her total AD to all units in front of her.
MOONLIGHT: Champions and large monsters affected by Diana's abilities are afflicted by Moonlight for 3 seconds, granting sight of them for the duration and 40 / 60 / 80% bonus attack speed against them. Additionally, every 3rd auto-attack on a Moonlight affected unit deals 20 - 250 (based on level) (+ 80% AP) bonus magic damage.
Notes
Possibility of including procing on-hit effects to her cleave autos. Don't know how would this come out balance wise. Her jungle clear might bee too good if she procs machete bonus damage on everyone cleaved. Lifesteal is also debatable.
The Moonlight part of her passive is basically a modernization of the old one.
Q - CRESCENT STRIKE
TARGET RANGE: 900
COST: 60 MANA
COOLDOWN: 10 / 9 / 8 / 7 / 6
ACTIVE: Diana unleashes a bolt of lunar energy that travels in an arc dealing magic damage to enemies hit.
MAGIC DAMAGE: 60 / 100 / 140 / 180 / 220 (+ 80% AP)
Notes
Her Q, Crescent strike, is one of her iconic abilities and it's mostly untouched.
Base damage and AP scaling a bit up.
W - PALE CASCADE
EFFECT RADIUS: 200
COST: 60 / 70 / 80 / 90 / 100 MANA
COOLDOWN: 10
ACTIVE: Diana shields herself for up to 5 seconds and creates five spheres that orbit her for the duration, detonating upon contact with an enemy and applying a slow for 1 second which reapplyies with every orb.
SHIELD STRENGTH: 40 / 55 / 70 / 85 / 100 (+ 4 / 5.5 / 7 / 8.5 / 10% Diana's maximum health)
If all five spheres detonate, Pale Cascade's shield is reapplied, stacking with its original shield, and its duration is refreshed.
TOTAL SHIELD STRENGTH: 80 / 110 / 140 / 170 / 200 (+ 8 / 11 / 14 / 17 / 20% Diana's maximum health)
SLOW: 30% + 5% for every extra orb hitting them.
Notes
The ability gets the Ashe W treatment - more smaller orbs which allow better detection.
Pale Cascade lost all of it's damage because it made Diana do too much burst and her damage is now more loaded onto her auto-attacks.
It also now slows, giving her some CC on a basic ability which is quite necessary for a diver. She will still have very little CC compared to others and no hard CC in her basic abilities. Adding a max HP scaling instead of AP scaling encourages her to building tankier.
E - LUNAR RUSH
TARGET RANGE: 600
COST: 70 MANA
COOLDOWN: 12 / 11.5 / 11 / 10.5 / 10
ACTIVE: Diana dashes in a line, dealing magic damage to everyone she passes trough.
MAGIC DAMAGE: 80 / 120 / 160 / 200 / 240 (+ 40% AP)
Hitting an unit affected by Moonlight gives you an option to cast another E after 1.5 seconds.
Units can be damaged only by one E, but proc Moonlight on both instances.
The ability goes on it's normal cooldown after the second E is used.
Notes
Similar to Kled W in how it works.
Complete reset on Diana's old Ultimate and double the damage was a big problem because it gave her with her old W, too much burst. Again, a lot more of her damage should be in her auto-attacks now, so the damage of E is also adjusted.
The first E is now also a skillshot giving her some safety in lane and the option to do some crazy escapes.
Possibility of making her second E recast option start at 3 seconds and scale down to 1.5 with champion level (for comparison Kat E cooldown reduction is 3 seconds at level 1). She might be too oppressive in lane if she can retreat after 1.5 seconds, but that might not be the case because she really wants to proc her passive in trades and for her to do that she needs 2-3 seconds anyways.