I can all hear u wonder. Why?

The reason to why is simple. Lucian is an AD caster. Lucian does high damage and can apply quick moves with his dodge. Lucian needs high manouvrability to place his skillshots and ult.

The build has to focus on all of these things. movespeed, often casting and applying damage.

One confusion in the lol community is that damage = damage. NO, wrong.
Damage = Damage - defense.

Ignore and lower more defense = do more damage.

One needs a balance in both to get most actual damage. That is what this built does.

The ghostblade is a very cool item on lucian early. it buffs his Ult, makes it easier to place it (using active) and with this build it gives much better early damage on champions like THRESH, BRAUM, LEONA and all those other nasty, tanky early game supports.

a lesson in armor and armor penetration ladies and gentlemen!

Armor = armor MINUS:
Armor reduction, flat
Armor reduction, percentage
Armor penetration, percentage
Armor penetration, flat

Endgame this build (with boots, not even triforce) has these magical stats:

49 armor Penetration (19.2 from runes, 20 from ghostblade, 10 from Black Cleaver)
41% armor penetration (6% from masteries and 35% from last whisper)
25% armor reduction (applied with ult on full team within milliseconds, from black cleaver)

How does this work:

Any ADC, Mage, Assasin and fighter usually has less than 100 armor lategame.

so:

ENEMY armor = 100
- 0 = 100
- 25% = 75
- 41% of 75 = 44.25
- 49 = -4.75 ARMOR

YES. MINUS 4.75 Armor

ARMOR formula:
100/(100 + armor)
100/(100 + -4.75) = 1.049

One applies 105% damage!

One still hits up to 350 AD or more with the bloodthurster in there and the attack speed from ghostblade + zephyr /+ trinity is great stuff.

An adc who rocks AD and attack speed but builds nothing in armor pen will get more ad sooner, yes. We all know the classic full AD Cait with 200 ad in no time, but her damage applies only for 50-70% and with this build, one keeps buying enough penetration to do almost 90-100% damage on all enemys throughout the whole game. That means an adc with 100 AD does the same damage then an adc with 200 Ad doing only 50%. These are extremes and experimenting with penetration and just flat AD will prove that the balance almost always tips in the favor of the penetration. The ONLy real dis advantage is around level 1-3 where the AD is slightly better. This is compensated by a little skill or just defensive farming untill level 3.

Lucian 'ultimate R' with this endbuild does a rough 4k damage, 5 something with buffs like ghostblade active, Nidalee heal, or nidalee heal + ardent censers buff. Experiments with supports like Nidalee and Janna (who buff his damage with their shield / heal) can get this lucian doing 6-7k damage with his ult. that means if u place it well u can nuke 2 or 3 champions before they can ever touch u, or whipe their tank and almost another champion before the fight begins.

Don`t believe me? try it out. This **** needs practice, but it works.

The downside of this build is a hard early game, it is hard to farm and u are susceptible to gank with these early low-ish stats. Skill, defensive early play, a good support, wards OR early ganks can all solve this problem easily.

Yes, other builds will do good early game damage. Yes other builds are easier to control. But mid and endgane, this build gives you the movespeed, cooldown reduction to be SUPER flexible and manouvrable on the field, your dodge and ult are almost always ready when u need them and with the Ghostblade active you can easily place ults, catch up and do a lot of more fun things.