Hi my name is Joey, also known as Fate Chosen.
I am a Gold 2 Top Main. I mainly play Darius.
This season alone in ranked I have played 100+ games as Darius.Now lets get this started.

PROS

High damage output
Tanky
Very good early game
Dunks everything.

CONS

Not a carry.
Not much mobility.
Easily Gankable.
Kinda falls off later game.

Building Darius is pretty straight forward. But along the way some games you may have to build differently then other times.

Longsword Start

Longsword start on Darius is very recommended as it builds into many items in your core build Such as, Ravenous Hydra, Trinity Force. It also has other value building such as Hexdrinker. The health potions it also gives gives you an advantage when trading with opponents.

Cloth Start

Cloth and 5 pots are good when going in a lane you dont expect to win, Example: Jayce.
To be honest I would only go this against a Jayce. But it is still good, you have high sustain since 5 health pots and then you have the armor to tank the auto attacks

Situational Items

There are many good items for Darius but we only have six inventory spaces so we have to maximize the dunkage potential with the best of the best items. Sometimes this can be tricky.

Randuins Omen is a good item, some would even say better then sunfire. While in some situations yes, but not all! Randuins is very good when you already have enough damage on your team and you need that little more umph in your Defense stats. It is also very good when against an enemy team that is very auto attack based. But Sunfire cape is better when you want to be more aggro, imagine randuins as Sunfires older,bigger brother while Sunfire is more rowdy and damaging Randuins is more stout and stubborn.

Guardians Angel is a good item when wanting to carry your team. It offers okay stats with a juicy passive. I don't have much to say on this item. It's good but as I have said, situational.

Black Cleaver is an item I haven't fully used yet, I have played enough games to know its not as good as the big tons of damage trinity force. But it does offer a better speed boost.. and really good armor pen. hmm. And pretty good damage and tank stats. More testing shall be done on this item!

Thornmail is pretty self explanatory, they have more AD than there are stars in the universe? GET THIS ITEM! Or they just have a Nasus, screw Nasus.

Maw of Mali is an item that is pretty hated, and I can't help but to feel sorry for this little guy. The stats are okay, its more the early game when you build its smaller counterpart. The shield it gives you against AP'S early game is really good. I can't even count how many times this little sucker has saved my butt.

Spirit Visage is like Randuins Omen but its magic resist counterpart. When they have too many AP's or your team already has enough damage, build this item!

Boots

There are 3 boots that are really good to build on Darius, all server there own purpose.
Mercury Treds (Adidas) are good against a team with heavy CC and AP they will get you out those sticky situations.
Boots of Swiftness (Jordans) Are the more carry boots, they are for when you are the most fed on your team and you need to be the man who picks up your team and carries them to victory. They are for chasing your opponents down and DUNKING them.
Ninja Tabi (Nike) Are good when you need those heavy auto attackers on the enemy team.
I highly recommend them against teams that rely heavily on the adc.

This is where Darius shines, he is the playground bully. You want that CS? TOO BAD! Q them so they QQ away.

But in all seriousness, Darius's laning phase is crazy! His early is good, and then he hits 6 and he is godlike! Basically what you wanna do as Darius is harass you lane opponent so much he wishes to have just one cs without getting melted. Darius has many combos, Such has E, W then Q when they are walking away to get that extra damage off. Thats what I call The Swish.
You wanna preform the Swish. alot. As Darius you wanna ward as much as possible as pesky jungles wanna come ruin your fun. And if you want maximum damage when doing the Swish auto attack in between abilities. Another combo is the DUNKMATE The DUNKMATE is where you walk up to your enemy while they are csing, auto attack them, while they run away like cowards Q then E them back W then finish them with DUNK! Also auto attack them while preforming this combo.

If you wanna see some League content I have a bunch on my Youtube channel where I upload there frequently. Here is my Youtube.
I love feedback so dont be afraid to comment and tell me your opinion. This is the first guide that I have made so I am looking to improve it and get better at guide making in general!
Also if you have any more questions feel free to add me on League my IGN is Fate Chosen on NA!
I will also update this as much as I can as time goes on!
Hope this guide helped! :D