Welcome to my guide!

So, why become the D-train, why not remain your average Darius? Fear. You thought Darius was scary enough when he gets fed? What is he was chasing you down to your inevitable demise at 460 (550 or so with ghost) movement speed? The damage is still there, and your bleed stacks up faster with the small CDR and AS boost from zephyr. I've played quite a few games as the D-Train quite successfully now, he can require a slightly different play style (kiting required in some cases, quite easy with the movement though). This is my first guide on Mobafire, so any constructive criticism is appreciated.

+ Extremely mobile

+ Huge damage potential

+ The movement speed provides great escape

+ Easy to snowball

+ Very fun to play!

+ Scare the hell out of your enemies!

- Not your usual Darius build, requires a slightly different playstyle

- Not as tanky as the traditional Darius.

The movement speed quints should get you an extra 15 or so additional movement speed to start with, this coupled with boots can provide you with plenty of early game ability to chase, escape and harass with Q. I'd say the movement speed quints are core, and if you're playing ranked or draft then you can switch out the normal runes depending on your situation.

Ghost

This is the bread and butter of the D-Train, engage full speed and chase any runaways, this is what separates this Darius as the homicidal maniac from the more reserved players. If an enemy is low at the turret (One Q from dying) just engage your ghost and do a drive by Q, you don't even have to target them half the time, thus reducing your turret damage in the process.
Ignite

This spell works wonders with your bleeds and helps to aid your ult if you don't quite finish off the enemy in fights. Also take note the healing reduction with ignite, which in turn increases the severity of your bleed effects.
Exhaust

Not my usual pick, but can be useful against champions such as Xin Zhao, the slow isn't necessary in this build however.

Hemorrhage
Darius' passive adds stacks of bleed damage to the enemy whenever they receive damage from him. The way to ensure maximum damage is if you cycle your abilities so that you can maintain and gradually increase the stacks while in lane. Use Decimate, wait, and use Apprehend followed by Crippling strike to ramp up those bleeds! Continue to either basic attack or decimate every 3 or so seconds and watch your enemy bleed out.
Decimate

This is your main source of damage, get used to being able to cast this within the outer radius, use your improved movement speed to get into range then Q and escape to maintain harrass on the enemy. This is also a good way to keep your bleed stacks on the enemy
Crippling Strike
This ability works very similar to Shyvanas Q in that your next basic attack becomes instant, hence making it most valuable to use straight after a basic attack for maximum burst. It also slows the enemy,
Apprehend
This can be an extremely useful ability, which I save for when the enemy attempts an escape during an encounter, or when an enemy enters turret range. It is also useful for chasing down enemies and provides you with a great gap closer, follow it up with Crippling strike, then move slightly away to hit a maximum damage decimate and finish the enemy off.

Use your sheer early game power to harass and deny enemy farm, try to get in range and out again with your Q, and focus on farming and denying farm. Pay attention when your own minions are low as they will close in to take last hits, which you can use to apprehend them.

I generally try to farm as much as I can on darius, and assist other lanes when it feels necessary. Don't spend too much time roaming else you will lose the level edge, and take advantage of the jungle golems whenever possible for extra XP.

This can become hard depending on the team setup, but you still have the potential to decimate the team if they do not stay within a group, take advantage of stray champions and attempt to pick them off one by one. If not, you should be aiming to take out the squishier champions in the enemy team who are the highest damage dealers, I play this Darius as more of an assassin than a tank.