Darius is an excellent ad tank.He will be legendary with his abilities,a top notch team fighter,He is the best league of legends champion from noxus (in my opinion) this guide explains how to use Darius and show you the power of Darius

Pros Cons
Great harasser
Excellent in team fights I have no cons lol
An ultimate ganker
Farms very fast
A great carry
Non stop power

I will go 21/9/0 with Darius because you have great ad on offense and good hp on defense
Utility masteries are no good for Darius unless your pure tank because theirs no point of using utilities on Darius

ORDER
Decimate-1,3,5,7,9
Crippling Strike-2,8,10,12,14
Apprehend-3,13,15,17,18
Noxian Guillotine-6,11,16

Decimate can really harass your enemies as long as you have your passive on some enemies
Crippling Strike can really help you chase without problems unlike other characters you get damaged by turrets while chasing
Apprehend can help you pull enemies into your team and get a kill also you have an armor bonus
Noxian Guillotine Outstanding damage yo will destroy with your ult have 3 stacks of herrorhage on your enemy then unleash the power

Greater Mark of Strength-Gives you some extra ad so you harass your enemeies a little more
Greater Seal of Might-just like your your Mark of Strength harass your enemies more
Greater Glyph of Strength- all of these runes help you harass more lol
Greater Quintessence of Strength- Hooray more harassing with runes

Start off with a Ruby crystal to have good hp and play longer in lanes.Obvious why you need Boots of Speed.Evolve your crystal into a Phage for bonus ad.Get more ad with a bf sword.Then, turn the phage into a frozen mallet for hp and non stop slowness.Buy Ionian boots to have cdr to add stacks of herrorhage with your q.Turn your bf sword into a bloodthirster for decent ad and life steal.Buy more hp with a giants belt then turn that into a warmogs.Buy an atma's to gain armor,crit and a great ad bonus!Finally,buy a bf sword and get an infinty edge for excellent crit and ad plus u destroy with crit.

The end of my great Darius build. this is my 1st build ever so i aplogize if you think i dont have color or anything else good bye!!!