How to play Darius by a Sona main
First step you have to get this amazing skin. Dunkmaster Darius is what makes you think you're lebronLeagueoflegends when you play him
As Dunkmaster darius you have to repeat ten times the following sentence:
i'm here to dunk
i'm here to dunk
i'm here to dunk
i'm here to dunk
i'm here to dunk
i'm here to dunk
i'm here to dunk
i'm here to dunk
i'm here to dunk
i'm here to win dunk
Now you can get to the next step, what is best role for Darius? you're kidding? Top lane is garbage, Darius is an ADC he should be played bot lane. You need tanks with CC in your team, A LOT of CC that's why you let your top laner pick maokai or malphite or something like that You on the other hand, are the tank killer with bonus AD on passive, 25% armor penetration, black cleaver and tons of true damage to dunk them.
Next step: you have to make sure you get a support with all in and CC, while banning 
who's impossible to lane against as well as 2v2. Once you get 
in your team you can destroy anyone in 2v2 if you and your support play well and don't miss anything.
You also need a ranged midlaner bringing magic damage to siege as you know you can't siege without a ranged champion
"but rubick, my midlaner instalocked 
and we don't have any ranged champion to siege" welp son you may call it GG and either dodge or afk.
Here is what your team should look like: 
is a great pick as he allows darius to dash, and can set up bushes to siege and help
Once you an your support are level 6, there is nothing the enemy team can do, but gank as 4 or 5
if the enemies decide to gank as 3, then you can simply call your lane your house like Dunkmaster darius says. If the enemy jungler isn't 2 level ahead, then simply 2v3 them while trying to get noxian might bonus AD, then dunk them all and tell them that IT'S MY HOUSE, i mean YOUR HOUSE
every time that YOUR HOUSE is ready then tell your support to all in and use YOUR HOUSE to dunk them
if your dunkmaster sens tells you that you're going to poked hard while your support has no sustain like thresh, then you may take 
to increase your sustain, what's more you also give more gold to your poor support.
then what will be your first item? yes we all know darius's first item
it's obviously 
as an adc you want to do a lot of damage, and trinity force gives you a good burst of damage with sheen (darius is top 3 highest base ad) and crippling strike. Trinity force is also a great attack speed item to get noxian might faster as darius attack speed sucks, this is why YOU HAVE TO get at least 24% attack speed from runes
"but rubick, i'll have a bad base ad and i can't last hit" fear not friend, after some games you'll be used to it and you will be able to farm without AD runes.
afterward, 
will be great in mid game to kill tanks even better, however if the enemies have 
i suggest replacing it with 
this is a great fuck you to healers while having a good armor penetration with apprehend's passive
latter, you want to get defensive items, 
this is a must-built because darius base ad is extremely high, which means not only this will save you from burst, but also increases your AD, sheen damage, and therefore your house damage
Be aware that your house damage sucks A LOT before 5 stacks, the damage is really miserable so don't try to Killsteal kills with your ulti if you have 1 stack on it, as you will fail and your ulti will go on cooldown
after some training, you'll become a onetrick darius easily
support = ez win
