Darius is one of the more abused champions out there. I mean he's got a pull in, slow, and that Ult. But due to his lack of mobility, he can easily be ganked. So the obvious thing to do is too build him tankier, so that he can last longer in battle, get those blood stacks in, and dunk the hell out of anyone. But at the same time, adding in a little Health and Mana regen. won't hurt.

When buying runes, go for hybrid attack/health. Life steal quints aren't too bad either.

Most people play Darius with an offensive Mastery. You could, but once again, it's important that Darius stays alive longer in fights, so go for a defensive Mastery build, with a point going for each of your Summoner Spells (whether it be Flash, Ignite, Ghost, etc.)

Darius seems like he needs to be built pure AD, but he actually doesn't. His base damage is pretty high, along with runes and a Bloodthirster, you're pretty much set in the damage field. Build him with a lot of health, starting with Spirit of the Ancient Golem, then Warmogs, the Locket of the Iron Solari for the the finishing touches. After you get these items, it's safe to go back to AD stacking.

Darius has one of those pain in the *** passives that acts as a buff, and at the same time, it does over time damage over 5 seconds. Each of Darius's spells applies a stack of Hemorrhage to the target, up to a maximum of 5 stacks. At max stacks, Darius's ultimate does twice its original damage, making it a priority to get all 5 in before you ult. His other moves are Decimate, Crippling Strike, Apprehend, and his troll of an ult, Noxian Guillotine. His spells are set up so you can burst a ton of damage, while being able to apply Hemorrhage, and finishing with Noxian Guillotine. Whenever you are about to start a fight (laning or roaming), start with Decimate, but keep about 1 inch from your target, as the spell deals most damage at the outer ring of its range. Follow up with a Crippling Strike, but don't use Apprehend until they try to run off. It has a long cool down, so it'll be a pain in the *** when you need it, but it's not up. Keep applying stacks and when you see your target has about 3-7 bars of health, dunk em with your ult.

All of Darius's skills are pretty badass, but his Decimate is his signature. Get a point in it first, and follow with one in Apprehend to help you get an early kill. Once you hit level 3, hit up Crippling Strike. After that, upgrade your ult when it's available, and try to max out Decimate first, then Crippling Strike, and lastly Apprehend.

Summoner spells are really important for Darius, as it provides a method of escape. Make sure you have either Flash or Ghost (or both). As a second choice, I'd take Ignite, as it couples greatly with your over-time Hemorrhage damage. Or you can take Teleport, if you like to split push. Just make sure there are wards near all enemy turrets. Teleport to the wards, clear minions waves, destroy turret in less than 10 seconds (spam your W), then recall out of there. Simple. I wouldn't recommend any other Summoner spell, unless you really know what you're doing.

Farming is relatively the same with Darius as any other champ - just last hit. But when your attack is high enough, make your way to the middle of an enemy minion wave (between the casters and the melees), and Decimate. One Decimate at about 260 AD will bring regular minions to about 1/3 of their health, letting you one hit kill them all with your auto attack. Don't abuse this though, especially early game, as it eats up mana.

Darius is capable of being an offtank, partly because of his Apprehend, which works wonders in team fights. Whenever someone is stupid enough to get close, Apprehend them right in the middle of your team during a team fight. After said champ is slaughtered, proceed with next target. As Darius though, try to avoid being right in the middle of the enemy team, as CC's can hit you, and when they do, the enemy team will tear you a new ********.