First, I want to say thank you for viewing my guide.
My name is Powell, i'm currently 17 and Plat V in SG Garena server.
I'm currently ADC main and would love to improve more.
This is my first guide in MobaFire.

9 Attack Damage Marks
9 Armor Seal
9 Magic Resist Glyphs
3 Attack Speed Quints.

18-12-0
Very Standard.

Ferocity

Fury: Great on all ADC Champs.
Feast: Good after you trade and you want to sustain in lane right?
Vampirism: Good with all ADC, doran's blade to sustain more.
Bounty Hunter: Get a double kill in lane, snow ball.
Battering Blows: You need this on all ADC champs.
Fervor of Battle: People debate on this a lot saying taking warlord can help you win a lot of 1v1 because of the extra life steal you get each double shot, but what I think is that if you burst an ADC to half hp with only your E, Double shot, Q, Double shot, they'll be pretty scared to fight you 1 on 1 and will try to back off. Then you can W and follow them with your R to finish them off.

Cunning

Savagery: You'll have an easy time csing.
Secret Stash: Extra HP, and Mana, why not? Don't go assassin, basically useless early game.
Merciless: Good for fighting also, that's what all ADC strive for.
Dangerous game: Say you're fighting 2v2 in lane, you killed their ADC, but their support has a lot of damage. Thats where Dangerous game comes in, it gives you Mana and HP for you to not die to a support and miss creeps (It saved me lots of times)

Youmuus: Early dominance, extra penetration and CDR can really help you a lot. Also the movement speed on this item is amazing.
Black Cleaver: After you finish this item you'll have tons of damage and CDR, also the movement speed helps you kite A LOT. The armor penetration helps you in team fight mid game.
Berserker's Greaves: Better than ionian boost, you get your double shots off faster, smoother in combos. Late game 30% CDR and 40% CDR and no difference.
Rapid

Don't get caught during team fight, mid to late game you only want to use your E to kite, not to dash in. Unless they have squishies and you are confident that you won't get hit by any cc (Or you have QSS) you can go in with your rapid fired cannon to deal massive damage to their frontline.

Lucian is an amazing champion early game and mid game due to his passive, lightslinger. If you play him right, you can dominate the game. Your culling does so much damage early, mid, and late game. If you can do your combos right, you'll output a lot of damage and with his kiting, you can kill lots of melee tanks.

Pros for Lucian: Lots of damage output early, mid game. If you're fed in late game with infinity edge you can pump out some serious damage.
Cons: If you fall off early game and get enemy fed, you'll have a hard time catching up. But just land good culling in team fight and you'll be fine.