无情铁手 is a strong crowd control ability in teamfights, but be careful who you pull. Pulling tanks such as Alistar or Amumu might backfire.
无情铁手 can pull people and minons over walls. It is useful for seperating enemies from their team or grabbing blue /red buff from a safer location.
无情铁手 is a strong initiation skill, but is much better at keeping people in the fight.
Although some believe that Noxian Guillotine is a gap closer since the visual effect looks like it, it is not. The range indicator only shows you how far you can use the ability. You are not moved in the process.
德莱厄斯 has strong bonus attack damage scaling, so building accordingly would be prudent.
Against an armor-heavy team, getting The Black Cleaver is great. It gives more attack damage that scales with your abilities, attack speed to apply Hemorrhage and the armor reduction to soften your targets up. However, the passive percentage armor penetration of Apprehend is less effective with armor reduction as armor reduction is applied before it in calculating the final effect of armor against you.
However, keep in mind that Darius is usually a prime target during teamfights due to the threat of Noxian Guillotine, and will die quickly if not built with at least some health and defensive stats. A high threat glass cannon in melee range will die most of the time.
Warden's Mail gives Darius some early sustain and the upper hand against AD-champions, since fighting back will make their escape even harder.
Darius has no movement abilities or other escapes, so getting a Quicksilver Sash will help against teams that try to lock you down with crowd control.
Trinity Force can be used to great effect on Darius despite the ability power waste, due to his low cooldowns and short range ability combos, it becomes easy to proc Sheen multiple times in a matter of seconds, and also provides some relief on his low mana problems.
Infinity Edge is sometimes picked up on Darius for the immense DPS it grants. When combined with Crippling Strike, it's possible to hit for 450% of your attack damage in a single strike. Although Infinity Edge is a very big investment for a bruiser, and should only be picked up if you're doing well.
Building armor to negate Darius' damage is not as recommended as against other physical damage dealers, since his ultimate deals true damage, his passive deals magic damage and he has passive precentile armor penetration. As such, building health is a more suitable counter.
Kayle is an absolute counter to Darius throughout the game. In lane, Kayle can kite Darius with Reckoning, Divine Blessing, and Righteous FuryRighteous Fury. This allows her to farm from a distance, win trades, harass safely, and out-sustain Darius. Should an extended fight occur which leads to Darius attempting to use Noxian Guillotine, 凯尔的Intervention can be used to block the damage from the skill, and force Noxian Guillotine on cooldown. At all ranks, Intervention has a lower cooldown than Noxian Guillotine, so it should always be available to stop Darius' Ultimate. Intervention can also be used on allies in teamfights to save them from Noxian Guillotine, allowing Kayle to stop Darius cold even past the lane phase.
Darius has a high damage output, but he lacks any form of escape mechanism. This makes Darius very prone to crowd control spells.
Remember that Darius has poor sustain. Try to harass him whenever you can to counter him from zoning you.
Remember that towers will automatically target any enemy champion who damages an allied champion within their range. This is important for countering Darius as it means he cannot approach a tower while Hemorrhage is applied to a champion within it's range. Use this to escape Darius by moving near enough to the tower to deny him a kill, or use it to attack Darius via tossing or pulling him to the tower.
Quicksilver Sash not only removes hard disables, but also clears a wide variety of debuffs. Once Darius applies five stacks of Hemorrhage and activates Noxian Guillotine, you can activate Quicksilver Sash while he's mid-cast to greatly reduce the incoming damage from the ultimate. This can potentially turn the fight in your favor and deny Darius the ultimate refresh he needs to continue a rampage.
Shields, especially high-health shields like those from 卡尔玛的Soul Shield can be used to deny 德莱厄斯的Noxian Guillotine a finishing blow, setting it on full cooldown and drastically reducing Darius's presence in team fights
Keep a close eye on low-health allies and/or allies with lots of Hemorrhage stacks, since those are likely to be the targets of Noxian Guillotine.
Shields/heals can be cast during the start up animation of Noxian Guillotine, since the casting time is long enough, and activating a shield too early can result in Darius simply waiting for the bonus health to expire.
Darius is exceptionally vulnerable to being kited, due to the cooldown and short range of Apprehend (the range is shorter in practice than the attack range of every ranged champion with the carry tag), and his lack of other gap closers.
Any sort of champion that can close the gap almost instantly on Darius (for example Jax or Fiora) is also acceptable because of the fact Decimate deals "less" damage inside its range.
Noxian Guillotine can't hit stealthed units. If you use an instant stealth spell while he is channeling his ult , Darius will stop his ultimate mid air, due to not having a target. However, it will not go on cooldown, like all targeted spells that lose their targets.