Hello guys! This is my first build/guide. not sure if the guide is good, so just take a better look at the build :)

Darius isnt a tank but he still needs a little arm and magic resist.
I am building Darius on ArmPenetration, so i am getting him not only ArmPen runes but masteries too.The other runes are AD, every dps AD champ need them, and they give you good start.
There are other good options like hp,movement speed or atack speed, but i dont realy like them. It gives you too litle HP, unlike the armor ones, they give you enough for early game.. so i think HP runes isnt good. Movement speed, if you start with "Boots of speed" you just dont need those runes, the dmg one are better. Attack speed, i am playing passive in the early game, so my opinion no need attack speed, but they are good choice if you play more agresive.

9 Offnese cuz "Weapon Expertise" and the other 21 in defense cuz of some hp, DmgReduction, MovementSpeed and CDreduction. Darius isnt a tank, but he is kind of a offtank, so he need a little defense too. There is other option- 19 on Offense just cuz the ArmourPenetration, and the other 11 in defense for some HP and dmg reduction. it is depending on your teammates, actually i prefer the ArmPen one, but think that the defensive(those in the build) are better for new darius player :)

Ghost and Ignite. Ignite is very helpfull and agressive offensive spell.Normally Exhaust is even better option but in my case, i take frozen mallet and darius can slow with W so exhaust isnt a good option. Ghost, you can change it with flash, it is depending on the player, i prefer ghost but flash is good too.

It is depending on the situation and on the player,My build is like a hard dying Dps. I get Aegis of the Legion cuz to up my Arm and MagicRes more than a 100 and make Darius hard dying with that much Arm MagicRes and HP. Black Cleaver, more faster stacking passive and more ArmPen. And.. thats it for my choice.
There are many other good items like.. Phantom Dancer(AtkSpeed),Infinity Edge(AD,crit),Zeke Herald(life steal.cdRed),Maw of Malmortius(MagicResist,AD,dmg absorb),Randuins Omen(arm, slow when they hit you),Warmog and Force of Nature(if building it more tank), Ninja Tabi(choose depending on the enemy which boots will be better - Mercury's Treads or Ninja Tabi)

And… think that is all.. I know that the guide isn’t very good, so just take closer look at the build.Just enjoy Darius and do some penta ;)