Darius is a very powerful champion of great strengths but glaring weaknesses.
- High damage with or without items. Will always be a damage threat.
- Useful hook that pulls enemies into your team for easy focus fire.
- Crippling slow on demand to peel for your carries.
- Can zone high priority targets enemies in team fights with the threat of his hook and his ultimate.
- Fast and efficient Jungle Clear.
- Strong ganking with his hook, slow and high damage.
- Unlike pure tank junglers, Darius can win most 2v2s fights, if one breaks out in a lane you're ganking. Darius is excellent in small skirmishes.
- True damage ultimate to eat through the armor of enemy tanks and bruisers.
- No good escape abilities. Fight or die.
- Slow, Easily kited, and not good at extended chases.
- Lacks sustain and natural defenses.
What role does jungle Darius play on a team?
Darius is one of the most misunderstood champions. So before discussing what role jungle Darius should play on a team, let's talk about what roles he can't play:
Darius is not a carry.
Some people consider Darius a carry, and they are wrong. Some simple math will show that by mid game, Darius only gets a ~0.46% damage increase per additional point of AD, the best damage stat for him (see chapter 8 for math). Crit and attack speed are not worth it as most of his damage is skills not auto attacks. Armor pen is also not worth building, as it only benefits his physical attacks, not his ult or his passive.
Carries can also deliver their damage easier due to their range and higher mobility. Darius' damage will fall off very hard if he is not ignored by the enemy team, because he cannot deliver his damage from range and his only gap closer (hook) is a very long cooldown.
More to the point: He's a melee range champion with no natural defenses, no natural escapes, his damage is backloaded, and he's easy to kite. You need to be very tanky to function, if you build glass cannon you will explode in any teamfight before you can do anything, and if you are too much of a damage threat, they will focus their CC on you and you will become useless.
While you can carry the early game with your strong ganks and the mid game with your high base damage, you can't safely build a lot of damage items and don't benefit much from them, so by late game you're either a meathead or dead meat.
Darius is not a cleanup champion
Some champions like master yi or katarina come in towards the end of the fight and clean up everyone. At first glance, Darius may look like this kind of champion, with his ultimate that resets on kills. This first impression is highly misleading.
Darius certainly has the kit to kill everyone on an enemy team if they stand still, however they're probably not going to stick around long enough for him to do that, His ult, while mostly unavoidable, has a rather long cast time which will immobilize him for a second, giving other enemies time to escape. It's not possible to play Darius as a cleanup champ vs competent players.
Darius does not dive the enemy carry
Darius also does not function as a diver in teamfights, like olaf, Jax, nocturne, Akali or Udyr: He can't dive into the enemy team, chase down the carry and kill them. Simply put, he's too slow, his hook cooldown is too long, and he has nothing in the way of defensive or escape abilities to allow him to pull that off safely. This is a common role that bruisers or assassins perform, and Darius is particularly bad at it.
So what is Darius? He's a tank and a bodyguard.
Simply put, Darius is a tank, and he packs the best kind of Crowd Control: Death. His massive damage without any items, including his true damage resetting ultimate, will cause any enemies to think twice before going near him. Even without building building much AD, you're still enough of a damage threat that you can't be ignored in teamfights. And if you build tank, they can't easily focus you down. And regardless of how much damage you do, the positional displacement from your hook is a huge threat to any squishy that could be easily focused down by your team.
What Darius lacks in CC he makes up in pure zoning capability. By building Darius as a tank, you turn your most glaring weakness: kitability, into a strength: zoning capability. If the enemy carries go anywhere near you, they will get hooked in, they will get decimated, they will get ulted, and they will die to focus fire from your team. So instead they will keep their distance while you kill the rest of their team. This zoning ability that Darius possesses simply by being so dangerous is a worthy substitute in teamfights for the crowd control abilities that most traditional tanks possess. And between his hook and his short cooldown slow, he's hardly lacking in CC himself.
In addition, by rushing boots of mobility, you can build Darius to perform another role that tanks typically perform: inititaion and ganking. These boots won't help you much for chasing people down after the fight has started, but they will help you gank, start fights, countergank, and get to the fight quickly to help your team if a fight breaks out while you're jungling. You can use these boots to seek out and find out of position enemy carries and then hook them into your team.
Darius functions best when he is not the primary damage threat on your team. He is much better as a secondary or tertiary darage threat. Due to being so easily kited, if you try to solo carry with darius, you will lose the game. As a secondary or tertiary damage threat, he still has the potential to kill enemies if ignored, and is much more likely to be ignored. If he is not ignored, he can soak up CC or focus fire which should have been targeted at a real carry with items, causing your team to win the fight.
Because of this, its generally better to get your team fed than you fed. So I recommend not stealing laner's creeps or spending a great amount of time splitpushing on Darius. Many bruisers are gear dependent, but Darius is not. He functions very well with only mobility boots and a support tank item or two like aegis and/or locket.