Well to that I say "why not?". I am a Diana main currently and have been for around 3 years now. She is super easy mechanically and has so much damage its hard to ignore the potential. In season 14, she is back better than ever in my opinion and can and will one-shot enemy ADCs and unfortunate little squishies. She does have some issues with bruisers like Darius/Fiora/Urgot but I believe in you :) you can build against them and have your team finish them off after bursting them down and running away.

Combo #1: Crescent Strike > Lunar Rush > Auto (you can use the second Lunar Rush dash to disengage by dashing to a minion closer to your turret)

Combo #2: Auto minion x2 (to trigger Moonsilver Blade) > Crescent Strike > Lunar Rush > Auto > Lunar Rush > Auto

Combo #3: Crescent Strike > Lunar Rush > Pale Cascade > Auto

Combo #4: Crescent Strike > Lunar Rush > Pale Cascade > Auto x2 > Lunar Rush > Ignite > Auto

Combo #5: Crescent Strike > Lunar Rush > Moonfall + Ignite > Auto > Lunar Rush > Pale Cascade > Auto x2

Lich Bane, Stormsurge and Shadowflame: These are Diana's core items and grant you a tonne of damage and burst to take out the enemy back line. The synergy these items have with Diana's kit is amazing.

Nashor's Tooth: Great for split push and even in cases where you just want that extra attack speed to make better use of your passive Moonsilver Blade.

Morellonomicon: Take this into heavy healers.

Liandry's Torment: I like to build this for when the enemy has a tanky team comp (even if it is just 2 tanks) as you will not be able to burst them down.

Zhonya's Hourglass: This is obviously good into AD assassins but it's active is useful for engaging without worrying about being immediately shut down. Diana has excellent engage but lacks a reliable disengage mechanic.

Rylai's Crystal Scepter: I like this item for the slow since it helps with being able to land Moonfall which you might find is hard to land at times due it having a very long wind up.

Riftmaker: Good all round with it's stats for Diana. Not a burst item but it helps with dueling and can be built along with tankier items so you do not have to sacrifice too much in terms of damage.

Rabadon's Deathcap: The favourite AP damage item. I usually do not build this last and like to build it either 3rd or 4th.

Spirit Visage: Beef up Pale Cascade with an even better shield.

Abyssal Mask: I like this defensive item when going into heavy AP comps but also for it's utility in teamfights and to buff your magic pen which is feels great especially if the rest of your items (at least the core Lich Bane, Shadowflame and Stormsurge) are damage items.

Iceborn Gauntlet: Great well-rounded defensive item with a cool passive that slows. It synergises well with other health items which is useful into situations where you might need that extra bit of health to survive and create a really big problem for the enemy in teamfights.

BOOTS:

Sorcerer's Shoes: My usual choice.

Mercury's Treads: A good choice into heavy CC which is a death trap since Diana does not have good disengage.

Berserker's Greaves: For attack speed build.

Plated Steelcaps: Only take this if you really have to into comps where there are 3+ AD champions that are doing well.

I'm not a Diana expert, just a casual enjoyer. I cannot tell you for sure that this guide will help you climb but it certainly would help the more aggressive Diana players win their lanes and have some fun on the rift one-shotting ADCs (everyone loved that). So lock her in and give it a try or try out my builds and see what happens but don't come at me if it doesn't work, I'm just the messenger and by no means a high elo strategist.

Anywho, thank you for reading and checking out my little guide, good luck out there soldiers!