Necrophos
* Ursa can do damage very fast with his 
Overpower and 
Fury Swipes abilities, Necrohops will have taken large amounts of damage before he can use Ghost Shroud, And if Ursa has 
Skull Basher, Ursa will quickly demolish Necrophos before he can do anything to retaliate.
* Skilled and smart Ursa can bait Necrophos into using Reaper's Scythe on him, and with his 
Aghanim's Scepter upgraded 
Enrage that can negate 80% of the damage, Ursa will often survive and waste Reaper's Scythe.
Legion Commander
* Fury Swipes can give Ursa the edge in Duels.
* Enrage's instant cast time allows it to be used before Legion Commander initiates a Duel, causing Ursa to take almost no damage for a brief period of time.
* However, Duel stops Ursa from casting Enrage at the most critical moment
Necrophos
* Mana Shield can tank most of the damage from Reaper's Scythe; with sufficient mana, the kill threshold drops significantly.
* Necrophos has a movement speed equal to Medusa, and is easy to chase down with a slowing item in Medusa's inventory.
Legion Commander
* 
Mana Shield makes Medusa very hard to take down in Duels.
* 
Stone Gaze stops Legion Commander from Dueling altogether, regardless of who she targets.
Necrophos
* Outworld Destroyer is not exceptionally dangerous to Necrohpos because of his Ghost Shroud, but his 
Astral Imprisonment can save his allies from Necrophos's Reaper's Scythe, though only if he uses it at the right time, If an Outworld Destroyer is nearby, Necrophos should not use Reaper's Scythe unless he has banished himself, or has banished two heroes within 15 seconds
Legion Commander
* Astral Imprisonment prevents Legion Commander from killing her opponents in Duels.
Additional:
* Outworld Destroyer can save an ally hero caught by 
Duel with Astral Imprisonment, and he can inflict heavy damage on Legion Commander with Arcane Orb to aid his ally. However, if he gets caught, he is unlikely to survive the duel, due to his lack of durability.
Necrophos
* Necrophos struggles at clearing away durable illusions or summons. Meepo can overwhelm Necrophos with his many duplicates, especially in the later stages of the game, and his 
Earthbind will prevent Necrophos from getting away, even if he casts Ghost Shroud.
* Meepo's high burst damage from 
Poof can make it difficult for to Necrophos to stay alive, and as Necrophos excels in extended fights, he will not be able to do as much damage as he intends to.
Legion Commander
* When Legion Commander uses Duel on one Meepo, he can use his other Meepos to kill her. If he wasn't dueled, he can help the teammate who was duelled to give the teammate the damage instead of Legion Commander.
* However, if Legion Commander picked up an Aghanim's Scepter and she duels one Meepo, that might be the end of Meepo if Legion managed to gather enough damage from previous duels.
Necrophos
* 
Nether Ward causes Death Pulse to actually damage Necrophos rather than heal him. Meanwhile, Reaper Scythe's gigantic mana cost while Necrophos is near the Nether Ward can often instantly kill him.
* 
Nether Blast and 
Life Drain both make quick work of Necrophos's small healthpool, especially during Ghost Shroud. The latter also makes him an unappealing target for Reaper's Scythe, and can often force Necrophos to use it defensively as he has no other means of interrupting his channeling.
Legion Commander
* 
Decrepify on either hero stops Legion Commander from completing a Duel, and dissuades her from initiating Duels on ethereal allies.
* Life Drain can help Pugna's teammates win a fight, either by killing Legion Commander or replenishing her target's health.
Additional:
* Decrepify prevents Legion Commander from attacking allies during Duel, regardless if it's used on her or on the ally .
* Pugna can easily cast Decrepify, Nether Blast and Life Drain on Legion during the 4/4.75/5.5/8 seconds of duel
Necrophos
* 
Reaper's Scythe is very predictable and gives Dazzle plenty of time to react with Shallow Grave: Dazzle just has to keep a close eye on his allies below 50% health.
* However, Dazzle must be sure to use Shadow Wave on that ally immediately after, or they will die from 
Heartstopper Aura when the Shallow Grave ends!
Additional:
* Dazzle's 
Shadow Wave is a spammable healing ability that spreads around his entire team, slowing the death of his teammates as effectively as Necrophos spreads damage to them.
* If not immediately, 
Shallow Grave delays his ally from gradually dying to Necrophos's abilities, especially Reaper's Scythe.
* However, bear in mind that Dazzle's 
Poison Touch, Shadow Wave and 
Bad Juju all deal physical damage, and Dazzle has no abilities to help him deal magical damage at all, which can cause problems for Dazzle to kill Necrophos if he uses Ghost Shroud to protect himself.
Legion Commander
* Shallow Grave prevents Legion Commander from killing her opponents in Duels.
* Shadow Wave will heal an ally caught in a Duel, as well as dealing damage to Legion Commander.
Necrophos
* Heroes who possess abilities that can save targets from being killed by Reaper's Scythe: 
Abaddon, 
Bane, 
Outworld Destroyer, 
Shadow Demon, 
Omniknight, etc.
Legion Commander
* 
Purification prevents Legion Commander from killing her target, and will always hit her during Duels.
* 
Guardian Angel completely wastes Duel's duration and can save an ally across the map when upgraded with Aghanim's Scepter.
Additional:
* Both Guardian Angel and Purification are perfect counters against Duel.
Necrophos
* 
Disruption can save an ally from a fatal Reaper's Scythe.
* 
Demonic Purge can remove Ghost Shroud, making Necrophos vulnerable to physical damage and preventing him from regenerating health.
Legion Commander
* Heroes who can hide the Dueled target (Outworld Destroyer, Shadow Demon, 
Tusk, 
Phoenix with Aghanim's Scepter etc).
Additional:
* Disruption can save allies and mess up an initiation from an enemy Legion Commander. Using Disruption on your ally that is affected by Duel will leave her totally exposed without the benefit of the life steal from 
Moment of Courage. A precise decision to Disrupt Legion Commander or her victim is crucial to waste Duel's potential.
* Demonic Purge cannot be dispelled by a hard dispel from 
Press the Attack, which in turn can be dispelled by your ultimate.
Necrophos
* 
Ice Blast completely nullifies any healing, making Necrophos unable to stay in a teamfight to sustain his teammates (and himself) or deal gradual damage to the enemy, else he be faced with a quick death if focused on.
Legion Commander
* Heroes with global abilities can give Legion Commander's opponent an edge in Duels from anywhere on the map: 
Nature's Prophet, 
Ancient Apparition, 
Zeus, 
Invoker, 
Treant Protector
Necrophos
* Necrophos' 
Ghost Shroud increases the magic damage taken by Necrophos.
* If Zeus builds both an 
Ethereal Blade and 
Veil of Discord, it almost always guarantees a kill.
Legion Commander
* Heroes with global abilities can give Legion Commander's opponent an edge in Duels from anywhere on the map: Nature's Prophet, Ancient Apparition, Zeus, Invoker, Treant Protector
Necrophos
* During the laning stage, Oracle's 
Purifying Flames nullifies any damage that Heartstopper Aura might inflict.
* 
Fate's Edict and 
False Promise can protect an ally from Reaper's Scythe.
* Oracle can dispel Ghost Shroud with 
Fortune's End.
Additional:
* Fortune's End can dispel Ghost Shroud, negating the skill's utility. Also it's worth noting that Necrophos takes additional magic damage when in Ethereal state, which makes Purifying Flames a powerful nuke against him.
* Fate's Edict fully negates the damage from Reaper's Scythe, which its own delayed animation makes it relatively easy to predict and nullify.
Legion Commander
* Fate's Edict prevents Legion Commander from attacking for a few seconds, potentially saving Oracle's ally.
* Fortune's End dispels Press the Attack's healing and attack speed buff, as well as the movement speed bonus from Overwhelming Odds.
* False Promise protects allies and prevents Legion Commander from winning Duels and gaining bonus damage.
Additional:
* Provided that the enemy team does not have an 
Axe, Oracle can guarantee that his ally survives for the duration of the Duel with False Promise and has decent nuke potential to help ally to win a Duel. He can also disarm Legion Commander with Fate's Edict.
* Oracle can dispel enemy buffs like 
Overwhelming Odds and Press the Attack with Fortune's End.
Legion Commander
* Heroes with long disables, like 
Lion, 
Night Stalker, or 
Legion Commander, can prevent Oracle from using spells or items.
Necrophos
* Tornado allows Invoker to purge Necrophos's Ghost Shroud, nullifying any benefits he could get out of it
* E.M.P. allows Invoker to burn Necrophos's mana, preventing him from using his abilities constantly
Legion Commander
* Invoker's spells will disable and destroy Legion Commander while she's locked in a Duel.
Legion Commander
* Heroes with long lockdowns: 
Shadow Shaman, Legion Commander.
Legion Commander
* 
Gravekeeper's Cloak protects Visage from Legion Commander's attacks for most of Duel's duration.
* Chain stuns from Visage's familiars prevents Legion Commander from winning Duels.
Legion Commander
* 
Cold Embrace saves allies from dying in Duels.
* 
Winter's Curse turns Legion Commander's high damage against her allies, giving the enemy team little time to react.
* However, Winter Wyvern lanes very poorly against Legion Commander due to Press the Attack removing all the debuffs she can give. Winter Wyvern also has little chances of surviving if she gets Dueled herself.
Additional:
* Cold Embrace is very effective against Duel.
* Also, casting Winter's Curse at Legion Commander while an ally is in a Duel will stun her for most of the duration, possibly preventing lethal damage dealt to your ally. It can also turn her high-damage against her teammate.
Necrophos
* Using Reaper's Scythe against Wraith King is a bad idea for Necrophos as his Reincarnation can waste it. And when upgraded with Aghanim's Scepter it can delay the deaths of allies.
Additional:
* Reaper's Scythe can't kill Wraith King while Reincarnation is off cooldown
* In the laning stage Vampiric Spirit can out-heal the slow {tooltip:DoT|Damage over Time} from Heartstopper Aura.
Legion Commander
* 
Wraith King's 
Reincarnation allows him to severely punish Legion Commander after he revives, as her abilities are on cooldown. Legion Commander is still awarded a Duel win if Wraith King reincarnates.
Additional:
* Wraith King makes a poor Duel target, as he can be already quite hard to bring down once, and then you have to worry about his second life.
* However, even if Legion Commander does win the duel when Reincarnation is off cooldown, she still receives the permanent victory damage bonus because taking down Wraith King's first life still counts as a "kill".
Necrophos
* Heroes who rely on physical damage are easily negated by Ghost Shroud: 
Phantom Assassin, Wraith King, 
Juggernaut.
Necrophos
* Heroes who possess abilities that can save targets from being killed by Reaper's Scythe: Abaddon, Bane, Outworld Destroyer, Shadow Demon, Omniknight, etc.
Legion Commander
* Bane has powerful single-target abilities that can help his allies win Duels, or at least cripple Legion Commander for the duration.
* Nightmare can waste Duel's entire duration as the dueled units transfer the Nightmare back and forth. This may be prevented if a non-Dueling unit attacks the Nightmared Dueler.
Additional:
* 
Enfeeble, 
Nightmare and 
Fiend's Grip all prevent Legion Commander from winning Duels, especially when Bane has 
Blink Dagger.
Legion Commander
* Heroes with strong dispels can dispel Bane's disables from their allies: 
Oracle, Legion Commander, Omniknight.
Legion Commander
* Battery Assault's mini-stuns can severely disrupt Legion Commander's attack animation when she enters a Duel, potentially saving Clockwerk (or his allies) and possibly even giving him an edge in securing a win himself.
* Power Cogs pushes Legion Commander away from Clockwerk's allies when she enters a Duel.
Necrophos
* Ghost Shroud is not a good defensive ability against Lina as all of her abilities deal magical damage.
* Lina has a very long range of attack, which completely overlaps the range of 
Death Pulse and Heartstopper Aura.
* However, once Necrophos gets 
Aghanim's Shard, he will gain access to 
Death Seeker which will allow him to turn into a larger Death Pulse that can be used to close the gap on Lina and kill her if she is not careful.
Additional:
* 
Laguna Blade's damage as well as damage from all of Lina's abilities will be greatly amplified during Ghost Shroud.
Legion Commander
* 
Mystic Flare can easily burst down Legion Commander while she is Dueling.
Legion Commander
* Solar Guardian can save allies who are being dueled and will interrupt her Duel initiation.
Necrophos
* Time Dilation while Death Pulse and Reaper's Scythe are on cooldown will make these abilities unusable for a long time, rendering Necrophos nearly useless.
* Necrophos cannot use Ghost Shroud while he is inside Chronosphere which makes it easy to kill him.
Legion Commander
* With armor items like 
Solar Crest or 
Assault Cuirass combined with Bash of the Deep, Slardar can easily tank the Duel, If not dueled himself, he can drop Legion Commander's armor during duel and/or buff his teammate and save them, leaving her only the choice of dueling supports which can also be saved with fast Blink into Slithereen Crush.
Necrophos
* 
Mana Drain depletes Necrophos's mana pool, preventing him from using his abilities.
* 
Finger of Death deals high magical damage, which becomes amplified by Ghost Shroud.
Legion Commander
* Heroes with long or multiple disables will prevent Legion Commander from winning Duels: Shadow Shaman, Lion
Legion Commander
* Lion is extremely dependent on his abilities. Silences like 
Silencer's 
Last Word, magic resistance like Oracle's Fate's Edict, and dispels like Legion Commander's Press the Attack all make his abilities less effective.
Necrophos
* Ghost Shroud amplifies damage taken from all of Grimstroke's abilities. Necrophos is particularly vulnerable to Ink Swell and Phantom's Embrace while in Ghost Shroud.
* Death Pulse works against Necrophos in lane by keeping his creeps alive and add damage to Stroke of Fate.
Necrophos
* Illusions make it difficult for Necrophos to target his Reaper's Scythe correctly, thus giving illusion heroes like 
Chaos Knight or 
Naga Siren an edge against Necrophos.
Legion Commander
* Song of the Siren lasts long enough to prevent a successful Duel (but only if Naga wasn't the target).
Legion Commander
* Heroes who rely on illusions will see them destroyed easily by Overwhelming Odds: 
Phantom Lancer, Chaos Knight, 
Terrorblade, Naga Siren
Legion Commander
* 
Lucky Shot can disarm Legion Commander and reduce her armor, which can reduce her chances of winning a duel. If an ally is targeted, Pangolier can simply use 
Swashbuckle to inflict it on her.
* If an enemy Pangolier casts a well-timed 
Rolling Thunder before Legion Commander can cast Duel, it might result in her chasing down Pangolier until his or her ultimate ends, whichever duration ends first, resulting in an open window for enemy allies to target Legion Commander, making her vulnerable and susceptible to any source of attacks. If Legion Commander has an Aghanim's Scepter in her inventory, the risk of wasting a solid 8 seconds would result in a futile duel.
* Dueling Pangolier is normally a mistake, Pangolier can disarm you in the duel, and potentially gain some Duel damage, Only duel Pangolier if at least 1 ally is nearby, and he is on low health, And even then, be wary, A good duel can easily turn against you with one Lucky Shot (Due to Lucky Shot lasting 4 seconds).
Additional:
* Swashbuckle can be used to disarm Legion Commander while she is Dueling an ally, granting her opponent a considerable advantage, Lucky Shot lasts 4 seconds at most wasting Legion Commander's entire Duel, (Or half, if Legion Commander has the Scepter).
* Legion Commander will try not to duel Pangolier alone, as she will almost inevitably lose, thanks to Lucky Shot's disarm, If Legion Commander wants to duel a Pangolier, she must be with atleast a teammate, and if she has her scepter, 3 or 4 teammates.
* Legion Commander is often with her allies, allowing you to rack up some considerable damage resistance with Shield Crash.
Necrophos
* Necrophos's Ghost Shroud does not prevent Muerta from attacking him while she uses 
Pierce the Veil, while making Necropohos even more vulnerable.
* Necrophos's Heartstopper Aura does very little to Muerta due to her quickly bursting down Necrophos and having a small health pool.
Necrophos
* Even though Luna has a hard time laning against Necrophos, his Ghost Shroud won’t protect him in teamfights because it will increase the damage from Lucent Beam and Eclipse.
* Luna is a natural 
Black King Bar wielder, and none of Necrophos's spells can bypass spell immunity outside of Heartstopper Aura.
Additional:
* Even though Luna has a hard time laning against Necrophos, his Ghost Shroud won’t protect him in teamfights because it will increase the damage from 
Lucent Beam and 
Eclipse.
* Luna is a natural Black King Bar wielder, and none of Necrophos's spells can bypass spell immunity outside of Heartstopper Aura.
Legion Commander
* A well-timed Eclipse before a Duel usually prevents Legion Commander from winning Duels, if Luna is the target.
* Meanwhile, when Luna is not a target, Eclipse and Lucent Beam can also help an ally win a Duel against Legion Commander.
* However, skilled Legion Commander will always buy a Black King Bar to block Eclipse and Lucent Beam or Aghanim's Scepter to reduce it's damage.
Additional:
* A well-timed Eclipse before a Duel usually prevents Legion Commander from winning Duels if Luna is the target. Luna can also buy 
Linken's Sphere to block Duel.
* Meanwhile, when Luna is not a target, Eclipse and Lucent Beam can also help an ally win a Duel against Legion Commander.
* Bear in mind, however, that skilled Legion Commander will always buy a Black King Bar to block Eclipse and Lucent Beam or Aghanim's Scepter to reduce their damage.
Necrophos
* A couple of long-range heroes with excellent laning like 
Mirana, 
Lina, 
Necrophos, 
Death Prophet. The key to success is sticking together and attacking Luna whenever she enters the range, without even giving Luna a chance to retaliate. Multiple long-range heroes is a reason to pick another hero.
Legion Commander
* Heroes that can keep Luna locked down for a long time can be a threat (she is very item and spell dependent): 
Faceless Void, Legion Commander, 
Doom.
Legion Commander
* Heroes with global abilities can give Legion Commander's opponent an edge in Duels from anywhere on the map: Nature's Prophet, Ancient Apparition, Zeus, Invoker, Treant Protector
Legion Commander
* Enigma can be a perfect counter-initiator with his ultimate. A perfectly timed Black Hole will turn the tide of any initiation, especially from heroes like; 
Spirit Breaker, Legion Commander, Axe, 
Puck, and 
Slardar.
Legion Commander
* 
Troll Warlord's melee bash and high attack speed can often help him and his allies win Duels against Legion Commander.
Legion Commander
* Heroes who can hide the Dueled target (Outworld Destroyer, Shadow Demon, Tusk, Phoenix with Aghanim's Scepter etc).
Additional:
* Walrus PUNCH! makes Legion Commander lose Duel easily, especially when she doesn't have 
Blade Mail. Tusk can also snowball dueled allies, preventing them from taking damage for a large portion of the duel's duration.
Legion Commander
* Magnetic Field prevents Legion Commander from getting wins with Duel.
Additional:
* 
Magnetic Field prevents Legion Commander from easily gaining wins with Duel.
Legion Commander
* Heroes who rely on summons will see them destroyed easily by Overwhelming Odds: 
Lycan, 
Arc Warden, 
Warlock, 
Chen
Legion Commander
* 
Paralyzing Cask can save ally from Legion Commander Duel's until she purchases Aghanim's Scepter.
* 
Voodoo Restoration can heal Witch Doctor allies from Duel's.
* 
Death Ward can help Witch Doctor allies from winning Duel's, if, he is not a target.
Necrophos
* Heroes that have small health pools and little to no escape mechanisms are even easier prey for Necrophos. Ghost Shroud's slow will allow him to catch him with them, and get nuked down with his abilities, even preventing retaliation due to Reaper's Scythe's stun. Such heroes include 
Crystal Maiden, 
Witch Doctor, Warlock or 
Shadow Fiend.
Necrophos
* 
Arcane Curse punishes Necrophos if tries to spam Death Pulse, increasing the duration of the slow and damage taken over time.
* Last Word heavily damages Necrophos and also silence him for a lenghty duration.
* 
Glaives of Wisdom will reduce temporarily Necrophos intelligence on each hit dealing hindering his ability to spam Death Pulse, also reducing his attack damage and mana pool; dealing increasing amounts of phisical and pure damage each time. Silencer will permanently steal Necrophos intelligence if Necrophos is killed by him or if he dies nears him.
* 
Global Silence turns Necrophos almost useless for a long time, allowing Silencer and his team to easily dispatch him, since Necrohpos heavily relies on his spells to survive.
Legion Commander
* Heroes that can disable or silence Silencer for a long time, such as Bane and Legion Commander, can lock down Silencer while their allies put him down.
Necrophos
* If Rubick steals Reaper's Scythe, he can turn the powerful ultimate back against Necrophos's team. Even his other spells are useful in Rubick's hands, giving him a sustain or a weak initiation/protection tool.
Legion Commander
* Heroes with low health will die easily during Duels, and can be farmed for damage in the early game: Crystal Maiden, 
Lich, 
Techies, 
Rubick
Necrophos
* 
Diffusal Blade is a core item on Phantom Lancer. And when combined with his numerous illusions, it allows him to rapidly deplete Necrophos's mana, rendering Necrophos incapable of doing anything.
* It can be difficult to single out the true Phantom Lancer among his army, giving Necrophos a hard time with aiming his ultimate.
* Even if his illusions are defeated, Phantom Lancer can simply create more of them at his disposal with almost no issues.
Legion Commander
* Heroes who rely on illusions will see them destroyed easily by Overwhelming Odds: Phantom Lancer, Chaos Knight, Terrorblade, Naga Siren
Additional:
* Overwhelming Odds deals high damage to Phantom Lancer's illusions.
* Duel's long duration prevents Phantom Lancer from using Doppelganger.
Necrophos
* Any hero with a low HP pool is easy for Tinker to nuke down: Crystal Maiden, 
Enchantress, 
Gyrocopter, Lion, 
Riki, Techies, Terrorblade, Necrophos, Invoker.
Legion Commander
* Heroes with abilities that blind or cause Legion Commander to miss will prevent her from winning Duels: Arc Warden, 
Keeper of the Light, Riki, 
Tinker
Legion Commander
* Press the Attack can dispel Laser's blind while providing great attack speed and health regeneration.
* Once caught in a Duel, Tinker, who completely relies on his spells to be effective, has little chances of survival with his low health pool and armor.
Necrophos
* Heartstopper Aura can do a decent damage overtime to Chen's High-Health-Creep Army, and Chen does not have any source of burst damage to fight back against Necrophos.
* Skilled Necrophos can purchase a 
Spirit Vessel to provide an AOE debuff that can reduce the healing from 
Divine Favor and 
Hand of God.
* Necrophos often builds 
Radiance, which combined with Death Seeker from Aghanim's Shard allows him to quickly clear Chen's creeps.
* Necrophos can often kill Chen's allies with Reaper's Scythe before Chen can save them with Hand of God.
Legion Commander
* Chen's fragility and low mobility make him an enticing Duel target.
* Overwhelming Odds and Moment of Courage can take advantage of converted creeps's numbers.
* With enough damage from Duel stacks, Legion Commander can also often kill any of Chen's unfortunate allies before he can use Hand of God.
Additional:
* Chen's frailty and low mobility make him an enticing Duel target.
* Overwhelming Odds and Moment of Courage can take advantage of converted creeps' numbers.
* With enough damage from Duel stacks, Legion Commander can also often kill any of Chen's unfortunate allies before he can use Hand of God.
Necrophos
* Reaper's Scythe can kill Terrorblade quickly before he has chance to use 
Sunder because it instantly disables an enemy hero on which it's casted.
* Even if Terrorblade succeeds to use Sunder on Necrophos, Necrophos can still protect himself from Terroblade's high attack damage with Ghost Shroud which can turn him ethereal and prevent Terrorblade from attacking him. Ghost Shroud also amplifies any healing Necrophos receives for it's duration, which in combination with Death Pulse and other healing items allows Necrophos to easily nullify Sunder's effects while Death Seeker from Aghanim's Shard can be used to escape from Terrorblade.
* Necrophos often buys Radiance, which combined with Death Pulse can help him deal with Terrorblade's illusions from 
Conjure Image and 
Manta Style. Death Seeker from Aghanim's Shard can also spread on Terrorblade's illusions upon impact.
* Terrorblade depends entirely on physical attacks and his damage output is 100% physical. Therefore, since he has no any sources of magical damage output and hates going for items that deal magical damage like 
Dagon, Ethereal Blade and 
Revenant's Brooch, Ghost Shroud will render him unable to damage Necrophos at all.
Legion Commander
* Duel's long duration prevents Terrorblade from swapping his health with Sunder.
* Overwhelming Odds deals high damage to Terrorblade's illusions.
Necrophos
* No matter how high Pudge builds up strength with his 
Flesh Heap, all it needs is for him to fall below a certain percentage of health for him to fall to Reaper's Scythe. Considering his constant self-damage with 
Rot, being around Heartstopper Aura will prove risky for an overconfident Pudge.
Additional:
* Heartstopper Aura is effective against high health heroes, and Pudge is no exception. Coupled with his self-damage from Rot, being around Heartstopper Aura could prove risky for Pudge.
* Regardless of how much health Pudge gains through Flesh Heap, Reaper's Scythe will often kill Pudge should his health fall below 40%, making Necrophos an ideal counter versus Pudge.
Legion Commander
* Legion Commander can use Press the Attack on an ally to dispel Dismember. The bonus health regeneration also partially counters the damage of Rot
* Duel can be used on Pudge whilst Rot is active, disabling toggling which may result in a lethal health drain that leaves Legion Commander with a successful duel.
Necrophos
* Death Pulse can easily wipe out Broodmother's spiderlings if they're too close while also offering Necrophos a source of regeneration for Broodmother's harass in lane.
* Ghost Shroud prevents Broodmother or her spiderlings from damaging Necrophos temporarily until Broodmother buys 
Nullifier or Revenant's Brooch.
* Heartstopper Aura will regenerate lost health and mana for every spiderling or spiderite Necrophos manages to kill.
Legion Commander
* Overwhelming Odds's damage stacks with each enemy unit in its radius. If this hits Broodmother and a large number of spiders it can deal significant amounts of damage.
* Moment of Courage has a high chance to proc if Broodmother and all of her spiders are attacking her.
* Duel can keep Broodmother in place long enough for Legion's team to kill her.
Additional:
* Overwhelming Odds is great at killing many stacked up spiderlings, thus giving Legion Commander a large buff.
* Duel is a reliable way to lock down Broodmother, preventing her from running into the treeline.
Necrophos
* Heroes that have small health pools and little to no escape mechanisms are even easier prey for Necrophos. Ghost Shroud's slow will allow him to catch him with them, and get nuked down with his abilities, even preventing retaliation due to Reaper's Scythe's stun. Such heroes include Crystal Maiden, Witch Doctor, Warlock or Shadow Fiend.
Legion Commander
* Duel is a great initiation to target Crystal Maiden with, as it prevents her from using Freezing Field or any other abilities and allowing the enemy team to quickly kill her before she can aid her team in a fight.
Necrophos
* Because Huskar tends to stay at low health to gain the maximum bonuses from Berserker's Blood, it makes him an exceptionally prime target for Reaper's Scythe.
Additional:
* Huskar is often at low health, making him easy prey for Reaper's Scythe.
* Ghost Shroud prevents Huskar from stacking 
Burning Spear, and if Heartstopper Aura stacks are active, can regenerate health lost to existing stacks.
Legion Commander
* Carries that can out damage Huskar will do well against him: Legion Commander, Faceless Void, Troll Warlord, Phantom Assassin.
Additional:
* 
Life Break is almost suicidal when used on Legion Commander, as it invites an instant Duel and Legion Commander herself is a natural Blade Mail carrier.
* Huskar's low survivability and mostly on low health make him particularly vulnerable to Legion Commander's high physical damage.
Necrophos
* Heroes that have escape abilities (such as 
Queen of Pain, 
Storm Spirit or 
Timbersaw) can be either nullified by Reaper's Scythe or a complimentary item for Necrophos (like 
Rod of Atos or 
Scythe of Vyse). If Necrophos is quick enough and enters range, they can quickly, if not instantly, die if they are not quick enough.
Legion Commander
* Duels prevents Queen of Pain from using Blink, which may force her to purchase a Linken's Sphere
* Because Queen of Pain is also not a right-click hero, Legion won't have much difficulties in duels.
* Press the Attack dispels Shadow Strike's debuff.
Necrophos
* Frequent healing from Death Pulse and 
Mekansm makes it difficult for Axe to finish off targets with Culling Blade.
* Ghost Shroud's instant cast time allows Necrophos to turn ethereal before being initiated on by Berserker's Call. This prevents him from attacking Axe while taunted, thus lowering the chance to proc Counter Helix.
* Axe's high health is relatively ineffective against Heartstopper Aura's percentage-based health degeneration.
* Reaper's Scythe stops Axe's game plan of using Berserker's Call multiple times and since he's in the middle of the fight, this spell is very easy to grab kills onto him.
Additional:
* Frequent healing from Death Pulse makes it difficult for Axe to finish off targets with 
Culling Blade.
* Reaper's Scythe negates Axe's tankiness, and can kill him quickly after initiation if Axe's health is low enough.
* Heartstopper Aura can be very effective against Axe due to Axe's high strength gain.
* However, bear in mind that 
Berserker's Call can prevent Necrophos from using his Ghost Shroud to defend his fragile self from physical damages. And Heartstopper Aura can unintentionally help Axe to trigger his 
Counter Helix more frequently while also hurting Necrophos with Blade Mail during activation.
* Nonetheless Heartstopper Aura is not considered as a normal attack, thus it will not trigger Counter Helix, so anyone who wrote the statement above should be awarded with MVP and considered a TI champion purely for the innovation of new mechanics.
Legion Commander
* Long lockdown is a great way to deal with Axe to prevent Berserker's Call from being used, heroes such as Legion Commander, 
Beastmaster and 
Primal Beast are good examples of this.
Necrophos
* Enemies that possess high defenses through magic resistance, damage reduction, or high regeneration will make it difficult to whittle their health down to get to Reaper's Scythe's threshold. Such heroes include 
Bristleback (although only from behind), 
Spectre, 
Ursa, and 
Dragon Knight.
Necrophos
* Reaper's Scythe and Heartstopper Aura deal percentage-based damage, ignoring Bristleback's high health.
* Heartstopper Aura's HP removal does not trigger Bristleback's passive.
Additional:
* Heartstopper Aura deals percentage-based damage flagged as HP removal, so it is not reduced by 
Bristleback, nor does it trigger passive 
Quill Sprays.
* Reaper's Scythe is very effective against Bristleback not only due to its percentage-based damage, but rather because it first stuns and then deals its damage, allowing Necrophos to position in front of Bristleback in time.
Legion Commander
* Duel makes Bristleback fight Legion Commander face to face, forcing him to take full damage.
* Press the Attack dispels the slow from stacks of Viscous Nasal Goo.
Additional:
* When dueled, Bristleback will have to face Legion head on, not allowing his passive Bristleback to come into effect.
Necrophos
* Heroes that have small health pools and little to no escape mechanisms are even easier prey for Necrophos. Ghost Shroud's slow will allow him to catch him with them, and get nuked down with his abilities, even preventing retaliation due to Reaper's Scythe's stun. Such heroes include Crystal Maiden, Witch Doctor, Warlock or Shadow Fiend.
Legion Commander
* Heroes who rely on summons will see them destroyed easily by Overwhelming Odds: Lycan, Arc Warden, Warlock, Chen
Legion Commander
* Press the Attack dispels Flaming Lasso.
* Batrider is unlikely to win a Duel in any stage of the game.
Necrophos
* Due to Doom's naturally high health, strength gain and common itemization for durability, Heartstopper Aura is particularly effective. The health loss is also large enough that, throughout all stages of the game, the aura effectively neuters the health regeneration granted by Devour.
* Necrophos can help to keep both himself and his allies alive during Doom through his natural regeneration granted by Heartstopper Aura (which is not disabled by Doom), or in the case of an ally, through his Death Pulse. Additionally, Necrophos is an ideal Mekansm carrier. Should one be bought, kills against Necrophos' team can be difficult to secure due to the damage-over-time nature of Doom and his abilities.
* Doom typically wants to be a hero that soaks attention from the enemy team and takes the role of an initiator and disabler. As such, Doom is an ideal target for Reaper's Scythe, as it is likely Doom will be at the fore-front of any fight.
Legion Commander
* Sniper's low mobility and lack of defensive abilities make him an easy gank target for the entire game, especially if Blink Dagger is picked up.
Necrophos
* Reaper's Scythe will turn Tiny's high health against him.
* Heartstopper Aura does substantial damage to Tiny as a result of his high max health.
* Ghost Shroud protects Necrophos from Tiny's physical damage with Tree Grab and Tree Volley.
Legion Commander
* Drow Ranger's low mobility and lack of defensive abilities make her an easy gank target in the early to mid-game.
* A Dueling Drow Ranger will lose her precious 
Marksmanship, reduce her damage output significantly, and will more likely lose that Duel.
Necrophos
* No matter how Tidehunter builds tanky items such as (
Guardian Greaves, 
Crimson Guard or 
Pipe of Insight), all it needs is for him to fall below a certain percentage of health for him to fall to Reaper's Scythe.
Legion Commander
* Duel is a great initiation to kill Death Prophet before she can cast Exorcism. Furthermore, Legion Commander often builds Blade Mail and can reflect Exorcism's damage to kill Death Prophet easily.
Legion Commander
* Press The Attack dispels the stun from Shackleshot.
* Duel can lock down Windranger before she can escape with Windrun.
* Legion Commander tends to go for Blade Mail, which returns the damage she takes from Focus Fire.
Necrophos
* Reaper's Scythe can kill Alchemist before Chemical Rage has the time to heal him.
* Ghost Shroud can prevent Alchemist from attacking Necrophos, as well as make him immune to Acid Spray and Unstable Concoction damage.
* Heartstopper Aura will do damage as long as Necrophos is alive based on health percentage, which is a problem for a strength hero such as Alchemist.
Necrophos
* Death Pulse and Ghost Shroud very effective against her physical damage.
* Heartstopper Aura and Reaper's Scythe are very effective against tanky Strength hero Marci.
Necrophos
* With high health and rarely buying Linken's Sphere or Black King Bar, Centaur Warrunner is a good target for Reaper's Scythe. However, Centaur Warrunner can resolve this problem by buying 
Hood of Defiance and it's upgrade Pipe of Insight to diminish its damage.
* Heartstopper Aura will do well against high health heroes such as Centaur Warrunner.
Legion Commander
* 
Searing Arrows and Clinkz physical damage items are almost suicidal when used on Legion Commander, as it invites an instant Duel and Legion Commander herself is a natural Blade Mail carrier.
* Duel locks down Clinkz for a long duration, preventing him from escaping with 
Skeleton Walk.
Necrophos
* Necrophos is a dangerous opponent to go against with. Regardless of how much strength Undying has gained from Decay, Necrophos can finish off Undying with Reaper's Scythe once Undying's HP falls below a certain threshold.
* Heartstopper Aura will do more damage to Undying if he gained strength from Decay, as it does damage based on a hero's maximum health.
Necrophos
* Ghost Shroud can be use both offensively to slow Lone Druid or Defensively to prevent Lone Druid and The Spirit Bear from attacking him.
* Heartstopper aura burns the Spirit bear High HP over time. Additionally, it can deal decent damage to Lone Druid during his True Form.
Necrophos
* Necrophos's Reaper's Scythe can finish off a low-health Morphling.
Legion Commander
* Heroes with low health will die easily during Duels, and can be farmed for damage in the early game: Crystal Maiden, Lich, Techies, Rubick
Legion Commander
* Heroes rely on their debuff to control the opponent will have a hard time against Press the Attack: 
Venomancer, 
Earth Spirit, 
Ogre Magi
Additional:
* Press the Attack dispels Venomous Gale and Poison Sting from Legion Commander or her teammates.
* Venomancer is an ideal target for Duel due to his lack of mobility and low starting health.
Legion Commander
* Because Duel requires both combatants to face each other, 
Bulwark's effectiveness will be increased by a huge margin, which makes it much more difficult for Legion Commander to win any duels against him.
* 
Spear of Mars and 
God's Rebuke pushes Legion Commander away during Duels against allies.
Additional:
* Bulwark immensely mitigates Duel, even with bonus physical damage, as Bulwark scales by percentage. Mars can also buy time for a dueled ally by pushing Legion Commander away with Spear of Mars.
Necrophos
* Necrophos' largely magical damage completely ignores Bulwark.
* Ghost Shroud protects Necrophos from God's Rebuke but more importantly stops Mars from being a threat in lane.
Legion Commander
* Legion Commander is both good and bad vs Mars, on the plus side she can dispel Spear of Mars with Press the Attack and is a good 
Silver Edge carrier. However, Mars is not an ideal Duel target, as Bulwark will force her to 1: Buy Silver Edge, and 2: Hit Mars with it before the Duel, allowing a skilled Mars to react, especially with 
Eul's Scepter of Divinity. In teamfights, Mars will happily draw attention after using his abilities, and tank the Duel with all spells on cooldown.
Necrophos
* Heroes that have high health but little to no magic resistance are easy prey for Necrophos, as no matter how high they build their health up, Reaper's Scythe will kill them outright as long as they fall under a certain threshold, and Heartstopper Aura will deal the same amount of damage regardless, decaying their health the longer they stay within range. As such, Strength heroes like Chaos Knight, 
Centaur Warrunner or 
Magnus are good targets for his ultimate.
Necrophos
* Innately fragile heroes will die almost instantly to Reality Rift while Chaos Knight has illusions active: 
Drow Ranger, Bane, Necrophos, Crystal Maiden.
Necrophos
* Heroes that have high health but little to no magic resistance are easy prey for Necrophos, as no matter how high they build their health up, Reaper's Scythe will kill them outright as long as they fall under a certain threshold, and Heartstopper Aura will deal the same amount of damage regardless, decaying their health the longer they stay within range. As such, Strength heroes like Chaos Knight, Centaur Warrunner or Magnus are good targets for his ultimate.
Legion Commander
* Heroes with strong area damage to destroy Phantasm illusions: Axe, 
Ember Spirit, Legion Commander, Phoenix
Legion Commander
* Heroes who rely on summons will see them destroyed easily by Overwhelming Odds: Lycan, Arc Warden, Warlock, Chen
Necrophos
* Heroes that have escape abilities (such as Queen of Pain, Storm Spirit or Timbersaw) can be either nullified by Reaper's Scythe or a complimentary item for Necrophos (like Rod of Atos or Scythe of Vyse). If Necrophos is quick enough and enters range, they can quickly, if not instantly, die if they are not quick enough.
Necrophos
* Heroes that have escape abilities (such as Queen of Pain, Storm Spirit or Timbersaw) can be either nullified by Reaper's Scythe or a complimentary item for Necrophos (like Rod of Atos or Scythe of Vyse). If Necrophos is quick enough and enters range, they can quickly, if not instantly, die if they are not quick enough.
Additional:
* Heartstopper Aura effectively negates Timbersaw's large HP pool as well as HP regen.
* Death Pulse together with health and mana regeneration from killed creeps helps Necrophos and his teammates survive Timbersaw's burst damage.
* As a tanky hero that stays in the middle of teamfights, Timbersaw is an easy target for Reaper's Scythe.
Necrophos
* Heroes that have small health pools and little to no escape mechanisms are even easier prey for Necrophos. Ghost Shroud's slow will allow him to catch him with them, and get nuked down with his abilities, even preventing retaliation due to Reaper's Scythe's stun. Such heroes include Crystal Maiden, Witch Doctor, Warlock or Shadow Fiend.
Necrophos
* Blade Fury blocks the damage done by Death Pulse and Reaper's Scythe. Additionally, Ghost Shroud decreases Necrophos's magic resistance, making him take more damage from Blade Fury.
Necrophos
* Heroes who rely on physical damage are easily negated by Ghost Shroud: Phantom Assassin, Wraith King, Juggernaut.
Legion Commander
* Duel pierces spell immunity and forces him to attack Legion Commander, making him unable to use 
Omnislash.
Legion Commander
* Special mention to Legion Commander, as she can lock down Void Spirit for a long amount of time without worrying too much about being killed by him during the Duel.
Necrophos
* Heroes who rely on physical damage are easily negated by Ghost Shroud: Phantom Assassin, Wraith King, Juggernaut.
Legion Commander
* Heroes rely on their debuff to control the opponent will have a hard time against Press the Attack: Venomancer, Earth Spirit, Ogre Magi
Legion Commander
* Heroes rely on their debuff to control the opponent will have a hard time against Press the Attack: Venomancer, Earth Spirit, Ogre Magi
Necrophos
* Heroes with area heals prevents Bloodseeker from bringing enemies low, and therefore deny him his Thirst bonuses and health return: Necrophos, 
Dazzle
Legion Commander
* Heroes with low health will die easily during Duels, and can be farmed for damage in the early game: Crystal Maiden, Lich, Techies, Rubick
Legion Commander
* Legion Commander with Press the Attack
* Heroes that can remove the Track debuff with their skills:
* Abaddon with 
Aphotic Shield and 
Borrowed Time
* 
Huskar with Life Break
* Juggernaut with 
Blade Fury
* Legion Commander with Press the Attack
* 
Lifestealer with 
Rage and 
Infest
* Naga Siren with 
Mirror Image
* Omniknight with 
Heavenly Grace
* Oracle with Fortune's End and False Promise
* Phantom Lancer with 
Doppelganger
* 
Slark with 
Dark Pact
* Ursa with Enrage
* 
Weaver with 
Time Lapse
* 
Tidehunter with 
Kraken Shell when damage received reaches the threshold.
Necrophos
* Enemies that possess high defenses through magic resistance, damage reduction, or high regeneration will make it difficult to whittle their health down to get to Reaper's Scythe's threshold. Such heroes include Bristleback (although only from behind), Spectre, Ursa, and Dragon Knight.
Necrophos
* Heartstopper Aura and Reaper's Scythe go right through Dragon Knight's armor.
Necrophos
* Enemies that possess high defenses through magic resistance, damage reduction, or high regeneration will make it difficult to whittle their health down to get to Reaper's Scythe's threshold. Such heroes include Bristleback (although only from behind), Spectre, Ursa, and Dragon Knight.
Necrophos
* Death Pulse can single out Spectre from her illusions, as well as heal his team against her. He also usually stands close to his allies for Death Pulse, effectively disabling 
Desolate.
Necrophos
* Anti-Mage can withstand magical burst damage much better than other carries, making him effective against nukers: Lich, Necrophos, Oracle, and 
Leshrac.
Legion Commander
* Duel renders Anti-Mage's escape capabilities with Blink and Counterspell useless. Blade Mail and Moment of Courage work well against Anti-Mage's relatively low health.
* A good initiation from Legion Commander and her team is enough to effortlessly kill Anti-Mage.
Additional:
* 
Counterspell offer no protection against Duel at all.
* Duel locks down Anti-Mage for a long duration, preventing him from escaping with 
Blink. One successful Duel initiation is usually enough for Legion Commander's team to kill Anti-Mage.
Legion Commander
* Heroes with abilities that blind or cause Legion Commander to miss will prevent her from winning Duels: Arc Warden, Keeper of the Light, Riki, Tinker
Legion Commander
* Press the Attack can dispel Blinding Light or Solar Bind from a hero.
* Duel can be used to instantly take Keeper of the Light out of a team-fight.
Legion Commander
* Heroes with abilities that blind or cause Legion Commander to miss will prevent her from winning Duels: Arc Warden, Keeper of the Light, Riki, Tinker
Legion Commander
* Another great threat to Riki since her Duel forces him to fight from the front and expose him for the entire duration, almost always guaranteeing an easy win (unless Riki has allies helping him).
* Moment of Courage can become hard to deal with as it doesn't cease with silence.
Legion Commander
* Heroes who can hide the Dueled target (Outworld Destroyer, Shadow Demon, Tusk, Phoenix with Aghanim's Scepter etc).
Additional:
* Legion Commander relies on her powerful attack and her Duel to be effective. But if Phoenix gets the jump on her first, she can find herself severely slowed, taking heavy damage, and find herself unable to Duel a burning Supernova.
* It must be noted that Press the Attack will both dispel the attack slow of Fire Spirits and grant her or whoever she targets bonus attack speed. This allows her to easily destroy a Supernova if caution is not taken to prevent this from occurring. As such, it would be a better decision to simply avoid a farmed or skilled Legion Commander instead of attempting to overpower her.
* If an ally is caught by Duel, Phoenix can use Sun Ray to heal the ally and damage Legion Commander, possibly swinging the Duel in their team's favor. Or with Aghanim's Scepter, Phoenix can save an ally from dying in Duel with Supernova and cancel the Duel as well.
Necrophos
* Phoenix constantly depletes its own health due to the health costs of its abilities. Unlike heroes that have a similar mechanic, Phoenix does not benefit from low health, nor does it really have a countermeasure for it. As such, Phoenix is a very vulnerable target for Necrophos to prey on, especially when caught off guard before it can cast 
Supernova.
Additional:
* Necrophos becomes a bigger threat the lower one's health gets, and unfortunately for Phoenix, most of its spells have noticeable health costs. Those costs, coupled with his Heartstopper Aura, means that staying in a teamfight for too long under Necrophos' presence will make Phoenix a more valid target for his ultimate, with its stun completely preventing any form of retaliation or protection. Necrophos players are also likely to buy more durability items such as Hood of Defiance, making him more able to withstand Phoenix's damage despite having no escape mechanisms.
* However, it is also important to remember that a Scepter-upgraded Supernova can help protect an ally from his ultimate.
Necrophos
* Heroes with one single-target abilities such as Wraith King, Necrophos, or Doom will struggle against Weaver's Linken Sphere.
Legion Commander
* Duel's long duration prevents Weaver from activating Time Lapse or escaping with 
Shukuchi.
Legion Commander
* Heroes that lack burst damage will have a difficult time taking down Monkey King, and fare badly against Jingu Mastery: Legion Commander, Lifestealer, Weaver, Wraith King
Necrophos
* Heroes with wide AoE abilities will reveal Monkey King through Mischief: Necrophos, Phoenix, 
Alchemist, 
Earthshaker, 
Razor, Tinker, Leshrac, Queen of Pain
Legion Commander
* Heroes that cannot move in fights such as a Dueling Legion Commander or anyone channeling a spell like Bane, 
Pudge, or 
Enigma are easy Sacred Arrow targets.
Legion Commander
* Heroes that can protect or dispel stunned allies such as Legion Commander, Outworld Destroyer, Shadow Demon and Oracle can reduce the effectiveness of Sacred Arrow.
Legion Commander
* Heroes with global abilities can give Legion Commander's opponent an edge in Duels from anywhere on the map: Nature's Prophet, Ancient Apparition, Zeus, Invoker, Treant Protector
Legion Commander
* Legion Commander's Overwhelming Odds deals damage for every Treant it hits, which allows it to easily wipe out large waves of them.
Legion Commander
* 
Static Link drains Legion Commander's accumulated damage, effectively neutralizing her overall primary advantage, and prevents her from winning Duels.
* 
Storm Surge's movement speed buff makes Razor and his allies harder to catch and initiate.
* 
Eye of the Storm, if used beforehand, will always hit Legion Commander during Duels, due to her forced proximity. This drastically lowers her survivability during Duel.
Necrophos
* Necrophos usually doesn't build itmes that give attack damage, minimalizing effects of Static Link.
* He can use Ghost Shroud to prevent Razor from attacking him with the stolen damage from Static Link.
* Razor is somewhat vulnerable to magical damage, and Reaper's Scythe prevents him from escaping with his high movement speed when things get dangerous.
Necrophos
* The huge physical damage taken from 
Vendetta will force Necrophos to use Ghost Shroud, which is good for a followup with Dagon and Ethereal Blade, both of which are common items on Nyx Assassin.
* Using Ghost Shroud also sets Necrophos up for a 
Mind Flare or 
Impale.
Legion Commander
* Duel's long duration prevents Nyx Assassin escaping from Vendetta. With Aghanim's Scepter, she can also bypass 
Spiked Carapace.
Legion Commander
* 
Tethered heroes are much harder for Legion Commander to kill in Duels.
* 
Relocate can cancel Duels and save allies.
Legion Commander
* Duel is very effective against Io due to its low health and armor.
Necrophos
* Viper does large amounts of magic damage over time, meaning that if a Necrophos uses Ghost Shroud, Viper's abilities will greatly reduce Necrophos survivability, and may actually kill him.
* By the same token, Viper can use his 
Viper Strike on Necrophos if he attempts to heal himself with Ghost Shroud, and depending on any other effects Necrophos may have from him, (IE:
Poison Attack,
Corrosive Skin), Viper can often kill Necrophos while he is in his Ghost Shroud.
* Viper's Corrosive Skin helps him take reduced damage from all of Necrophos spells that deal magical damage, which is his only source of damage.
Additional:
* Viper Strike prevents Heartstopper Aura from dealing damage or healing Necrophos.
* Viper's magic damage is amplified whenever Ghost Shroud is used.
* Corrosive Skin makes Viper tankier against Death Pulse and Reaper's Scythe.
Legion Commander
* Viper's frailty and low mobility make him an enticing Duel target and Corrosive Skin doesn't protect him against Legion Commander physical attacks.
* Press the Attack can dispel Poison Attack.
* Viper slows can easily negate by Overwhelming Odds movement speed.
Legion Commander
* Earthshaker's AoE stuns can save ally against Duel, forcing Legion Commander to spend Aghanim's Scepter or Black King Bar.
Necrophos
* Frequent healing from Death Pulse and Mekansm/Guardian Greaves or Pipe of Insight makes it difficult for Earthshaker to execute his combo with Echo Slam.
* Necrophos usually buys Radiance to improve their burning aura damage from Heartstopper Aura will usually disable Earthshaker's Blink Dagger prior to a teamfight, preventing him from initiating or re-initiating.
* Reaper's Scythe allows to kill Earthshaker while he blinks in, preventing him from executing his combo (although Earthshaker is rarely a primary target).
Legion Commander
* 
God's Strength makes Sven one of the worst heroes to Duel.
* 
Storm Hammer can be used to interrupt Duels.
* 
Warcry gives a big boost in passive defensive ability with the active component to nearby allies.
* With the Aghanim Shard Warcry also gives nearby allies passive increases.
Necrophos
* His Heartstopper Aura deals the same gradual damage over time no matter how high Sven builds his strength or health pool up, and should he fall down to a certain percentage, his high health will no longer matter if Necrophos manages to land his Reaper's Scythe, killing him instantly. But it is best if Necrophos can either catch him off guard before he can possibly use his Black King Bar (which is an item Sven players commonly purchase), or bait him out of it.
* Ghost Shroud prevents Sven from hitting Necrophos, and if he doesn't have his Storm Hammer available, it could make him completely immune to Sven and allow Necrophos to easily kite him around.
Legion Commander
* Heroes with long or multiple disables will prevent Legion Commander from winning Duels: Shadow Shaman, Lion
Legion Commander
* Pudge, Legion Commander and Axe will make the match a living hell for Shadow Shaman, since they are known for surprise attacks from the fog and quickly killing low HP heroes. They can also interrupt Shadow Shaman's channeling, Legion being especially problematic, as she can use Press the Attack on an ally who is hexed as well.
Legion Commander
* 
Atrophy Aura's percentage-based damage reduction greatly diminishes Legion Commander's overall damage output, even if she has won many Duels
* Legion Commander cannot get out the way of Firestorm because she is stationary.
Additional:
* Atrophy Aura makes it hard for Legion Commander to win Duels.
* 
Fiend's Gate can be used to save Underlord and his allies from a Duel or to intercept Legion Commander, because outside from Overwhelming Odds, Legion Commander has no other area-of-effect abilities.
Necrophos
* Reaper's Scythe and Heartstopper Aura deal percentage-based damage, ignoring Underlord's high health.
* Ghost Shroud protects Necrophos from Underlord's damage from Atrophy Aura, and also amplifies all the healing Necrophos receives.
Necrophos
* If he isn't silenced, Abaddon can use Borrowed Time to escape
Reaper's Scythe during the delay.
Legion Commander
* If he isn't broken (break), Abaddon can use Borrowed Time to waste Legion Commander's
Duel, As Borrowed Time has a shorter cooldown, Legion Commander can't win duels, effectively reducing her targets by one, Duel also means that Borrowed Time heals Abaddon for the duration of the duel, as Legion can't stop attacking.
Aphotic Shield and 
Mist Coil makes it hard for Legion Commander to kill Abaddon's teammates in Duels.
Borrowed Time makes Abaddon nearly impossible to kill in Duels, and often replenishes much of his health because Legion Commander cannot manually stop attacking during Duels.
Additional:
*
*