Sven
* Tanky melee heroes that can easily be kited, which allows Outworld Destroyer to deal heavy damage with Arcane Orb from a distance: 
Sven, 
Underlord, 
Bristleback.
Naga Siren
* 
Arcane Orb allows Outworld Destroyer's attacks to deal pure damage that can bypass Naga Siren's armor, and which can clear her illusions in no time.
* 
Astral Imprisonment can be used to harass Naga Siren by reducing her maximum mana and to prevent Naga Siren from escaping with Song of the Siren. Outworld Destroyer can also use Astral Imprisonment to protect himself from Naga Siren.
* 
Sanity's Eclipse will most likely instantly kill Naga Siren along with her illusions. Even if Naga Siren survives Sanity's Eclipse, it's mana allergy debuff will discourage Naga Siren from using her abilities as the mana allergy will heal Outworld Destroyer if she uses them for it's duration.
Sven
* Heroes who can take advantage of God's Strength being on cooldown are also not great matchups, such as 
Templar Assassin, 
Morphling and 
Huskar.
Naga Siren
* 
Waveform clear Mirror Image illusions from Naga Siren. And though 
Ensnare can prevent Morphling from using Waveform to escape, he can easily dispel it with 
Manta Style, a common item on Morphling.
* 
Morph allows Morphling to copy Naga Siren's abilities and combine them with Manta Style, a commong item for Morphling, to destroy Naga Siren's illusions. 
Aghanim's Scepter upgraded Morph also allows Morphling to create a strong illusion of Naga Siren that can do the same and which can also allow Morphling to close the gap on Naga Siren.
Sven
* Heroes that relies on armor or other type of physical damage negation are easy for Gyrocopter to take down during the early game with his magical damage: 
Axe, 
Dragon Knight, Sven.
Naga Siren
* 
Flak Cannon and 
Call Down can easily clear Naga Siren's illusions.
Sven
* Batrider often hides in the trees to initiate on a target. As such, he has a slight edge against heroes that have no scouting tools and cannot see him coming, such as 
Lion or Sven.
Naga Siren
* Many stacks of 
Sticky Napalm, combined with 
Flamebreak and 
Firefly, allows Batrider to destroy illusions from 
Mirror Image.
* If Batrider can manage to destroy all illusions from Naga Siren, he will be able to use 
Flaming Lasso on the real one, and will be able to drag her toward his team, potentially preventing Naga Siren from escaping with 
Song of the Siren.
Additional:
* Many stacks of Sticky Napalm, combined with Flamebreak and Firefly, allows Batrider to destroy illusions from Mirror Image.
* If Batrider can manage to destroy all illusions from Naga Siren, he will be able to use Flaming Lasso on the real one, and will be able to drag her toward his team, potentially preventing Naga Siren from escaping with Song of the Siren.
Sven
* Stone Gaze allows Medusa to easily kite and kill Sven.
* Mana Shield negates much of Sven's burst damage.
Additional:
* 
Mana Shield makes it very hard for Sven to burst her within Storm Hammer's stun duration.
* 
Stone Gaze makes it very difficult for Sven to fight Medusa at any stage of the game.
* 
Mystic Snake can slow Sven down enough for allies to capitalize on his commitment in a fight.
Naga Siren
* Medusa's 
Split Shot and Mystic Snake combined with 
Mjollnir, a common item for Medusa, will whittle down all of Naga Siren's illusions, including Naga Siren herself.
* Medusa's Stone Gaze can disable Naga Siren even for the duration of Song of the Siren and even if Naga Siren is spell immune, discouraging Naga Siren from even trying to use Song of the Siren to save herself or counter-initiate against Medusa.
Additional:
* Medusa's Split Shot and Mystic Snake combined with Mjollnir, a common item for Medusa, will whittle down all of Naga Siren's illusions, including Naga Siren herself.
* Medusa's Stone Gaze can disable Naga Siren even for the duration of Song of the Siren and even if Naga Siren is spell immune, discouraging Naga Siren from even trying to use Song of the Siren to save herself or counter-initiate against Medusa.
Naga Siren
* Heroes that build 
Diffusal Blade or can fit it well into their item build will also make Medusa much less tanky: 
Riki, 
Naga Siren, 
Terrorblade, 
Juggernaut, 
Spectre, 
Slark.
Sven
* Heroes who can stun Sven even with an activated 
Black King Bar can be an issue: 
Clockwerk, 
Beastmaster.
Naga Siren
* Heroes with long cast animations can be continuously interrupted by Battery Assault: 
Centaur Warrunner, 
Jakiro, 
Leshrac, Naga Siren, Underlord.
Sven
* Sven is very vulnerable to chain stun such as Lion, 
Shadow Shaman or 
Magnus.
Naga Siren
* Lion may upgrade 
Mana Drain, 
Hex and 
Finger of Death through Talent Tree and Aghanim's itens to make them affect secondary targets or turn them into AoE abilities. This can make things difficult for heroes like 
Phantom Lancer, Naga Siren and Terrorblade, who rely on illusion armies.
Additional:
* Both Hex and Mana Drain destroy Naga Siren's illusions in an instant, making it hard for her to teamfight or push against a team with Lion. If Lion chooses the AoE effect talent for Hex or the shard for multi-target Mana Drain, it can negate her pushing potential entirely.
* 
Earth Spike is an AoE disable with good damage. If used well, it can help distinguish the true Naga Siren by the damage they take (illusions take more damage).
Sven
* Heroes that rely on physical damage are ineffective against Dragon Knight due to his high armor: 
Phantom Assassin,
Bloodseeker, 
Lifestealer, 
Troll Warlord, Sven
Naga Siren
* Heroes whose attacks can affect multiple enemies at once will clear Naga Siren's illusions. Such heroes include Sven, Magnus, Dragon Knight, 
Luna, 
Medusa, Templar Assassin, 
Gyrocopter, 
Muerta.
Sven
* Heroes who thrive on teamfights can be a problem, such as 
Venomancer, 
Necrophos, Centaur Warrunner...
Naga Siren
* Heroes who are reliant on illusions: 
Chaos Knight, Phantom Lancer, Naga Siren.
Additional:
* Centaur's 
Retaliate will harm all attacking enemies, which will allow Centaur Warrunner to see which is the real Naga Siren.
* A well timed 
Hoof Stomp followed by 
Double Edge will clear all Naga's illusions and prevent Naga Siren from escaping with Song of the Siren.
Sven
* Melee carries during the laning phase: Sven, Slark
Naga Siren
* 
Keeper of the Light can stall pushes with 
Illuminate. This makes him strong against pushing heroes: Terrorblade Naga siren 
Nature's Prophet and 
Anti-Mage
Sven
* 
Cold Embrace saves any ally Sven initiates on and wastes the duration of God's Strength in team fights.
* 
Winter's Curse can be devastating to Sven's team, as his massive damage can take out a teammate before there is much time to react.
Naga Siren
* Dawnbreaker can easily clear waves of Naga Siren's illusions from Mirror Image with 
Starbreaker, 
Celestial Hammer and 
Solar Guardian.
* 
Aghanim's Shard upgraded Starbreaker will allow Dawnbreaker to dispel Ensnare and freely attack Naga Siren during Song of the Siren when combined with Black King Bar, a common item on Dawnbreaker.
* Solar Guardian allows Dawnbreaker to counter any attempts of Naga Siren and rejoin her team with Solar Guardian when they require it. Aghanim's Scepter upgraded Solar Guardian can also give Dawnbreaker's allies evasion while Dawnbreaker is airborne for it's duration, as Naga Siren mainly relies on direct attacks in order to deal damage.
Additional:
* Dawnbreaker can easily clear waves of Naga Siren's illusions from Mirror Image with Starbreaker, Celestial Hammer and Solar Guardian.
* Aghanim's Shard upgraded Starbreaker will allow Dawnbreaker to dispel Ensnare and freely attack Naga Siren during Song of the Siren when combined with Black King Bar, a common item on Dawnbreaker.
* Solar Guardian allows Dawnbreaker to counter any pushing attempts of Naga Siren and rejoin her team with Solar Guardian when they require it. Aghanim's Scepter upgraded Solar Guardian can also give Dawnbreaker's allies evasion while Dawnbreaker is airborne for it's duration, as Naga Siren mainly relies on direct attacks in order to deal damage. Solar Guardian can also be used after Naga Siren uses Song of the Siren near her allies to either escape from or counter-initiate against them.
Sven
* Undying can use Decay not only to reduce Sven's maximum health, but also to reduce the damage he can deal with his ultimate.
* Zombies spawned by Tombstone together with Flesh Golem slow Sven down significantly. Landing Sven's powerful but somewhat slow right-click on Tombstone would be a waste.
Naga Siren
* Mirror Image's illusions increase Echo Slam's damage.
Additional:
* Earthshaker's strong AoE abilities can clear Naga Siren's illusions, or at least make it easier to distinguish the real one by the damage they take.
* 
Echo Slam deals more damage against more enemies, which can be devestating against Naga Siren and her illusions.
Naga Siren
* All of Leshrac's abilities, especially 
Pulse Nova, can easily deal with Naga Siren's illusions.
* Aghanim's Scepter gives Leshrac access to 
Nihilism ability, that allows him to turn himself along with Naga Siren and her illusions to turn ethereal. And to make things worse, Nihilism can slow Naga Siren and her illusions, make them more vulnerable to magical damage and unable to fight back while Leshrac moves faster and does not take increased magical damage for it's duration.
Sven
* Pugna can save allies with both healing or by making them ethereal but needs to be careful of Sven's Aghanim's Scepter purge.
Sven
* Multicast Fireblasts over the course of fights are a decent nuisance to stall Sven's massive damage output.
* Bloodlust and Ignite gives Ogre Magi's team the movement speed difference needed to chase and/or disengage against a Sven and his 
Warcry.
* Ignite provides strong damage over time to pressure Sven early on in the laning phase and keep his health low, delaying his transition into the jungle. Ignite is also an easy way to disrupt 
Blink Dagger, Sven's most popular way of initiation.
* Ogre Magi's presence in the laning phase both in terms of damage and durability keeps high pressure on Sven in lane.
* Purchasing an Aghanim's Shard allows Ogre Magi to greatly reduce the burst damage of Sven, who tends to build items focused on damage per hit instead of attack speed.
Naga Siren
* Jakiro's damage over time abilities can clear Naga Siren's illusions and can hurt real Naga Siren even for the duration of Song of the Siren.
* Naga Siren is not a hero that likes to go for Black King Bar, and that makes her very vulnerable to Jakiro's damage over time in every phase of the game.
Additional:
* Jakiro's damage over time abilities can clear Naga Siren's illusions and can hurt real Naga Siren even for the duration of Song of the Siren.
* Since Naga Siren is a hero who barely goes for Black King Bar, this can make her very vulnerable to Jakiro's damage over time in every phase of the game.
Sven
* Sven can be easily kited since Weaver is a natural 
Linken's Sphere carrier and Sven relies on 
Storm Hammer to disable and kill a hero.
Sven
* 
Whirling Axes (Melee)'s blind makes Sven nearly useless in the early game and allows Troll Warlord to take him on comfortably.
* 
Battle Trance will mean Sven will never take Troll out in a 1vs1 with equal farm.
Additional:
* Berserker's Rage together with Troll Warlord's high attack speed gives Troll a high chance of rooting enemies, which allows Troll Warlord to man-fight Sven.
* Whirling Axes (Melee) provides a 60% miss chance, and the passive armor provided by Berserker's Rage makes Troll resilient to physical damage in early game. Sven's 
God's Strength is much less effective as a result.
* Beware that Sven can farm much faster than Troll Warlord by stacking ancients and clearing them with 
Great Cleave.
Sven
* Muerta's attacks during 
Pierce the Veil ignore Sven's Warcry.
* Sven using God's Strength can be completely ignored by using Pierce the Veil.
* Sven with Aghanim's Scepter will still not be able to dispel Muerta's Ethereal form during Pierce the Veil.
* However, Sven is a natural purchaser of Black King Bar that can protect him from Pierce the Veil and the rest of Muerta's kit.
Naga Siren
* Heroes whose attacks can affect multiple enemies at once will clear Naga Siren's illusions. Such heroes include Sven, Magnus, Dragon Knight, Luna, Medusa, Templar Assassin, Gyrocopter, Muerta.
Naga Siren
* Any long duration disables that can pierce through both, Pierce The Veil and Black King Bar are devastating against Muerta: 
Enigma's 
Black Hole, 
Dawnbreaker's Solar Guardian, Axe's 
Berserker's Call, Naga Siren's Aghanim's Scepter upgraded Ensnare and 
Reel In from Aghanim's Scepter, Jakiro's Aghanim's Scepter upgraded 
Macropyre, 
Bane's 
Fiend's Grip, 
Pudge's 
Dismember, 
Batrider's Flaming Lasso, Beastmaster's 
Primal Roar, 
Grimstroke's 
Soulbind, Medusa's Stone Gaze, Magnus's 
Reverse Polarity.
Sven
* Primal Roar takes Sven out of the fight completely, even with Black King Bar.
Naga Siren
* Timbersaw's innate durability provided by 
Reactive Armor is very hard to deal with as Naga Siren as she mostly relies on sustained damage rather than burst damage unless if she is played as Nuker.
* Timbersaw's high pure damage and low-cooldown area-of-effect nukes which are 
Whirling Death, 
Timber Chain, 
Chakram and 
Flamethrower from Aghanim's Shard can also destroy Naga Siren's illusions very fast.
* Timbersaw is a common 
Lotus Orb wielder which allows him to reflect Ensnare back at Naga SIren.
Sven
* Against her Untouchable, Sven is barely able to hit Enchantress even with his Black King Bar.
Sven
* Heroes that deal few, powerful instances of damage, like 
Oracle, Lion, or Sven, have a hard time breaking through Gravekeeper's Cloak.
Sven
* Fate's Edict cripples many heroes who rely on attacks, such as Phantom Assassin, Sven, or 
Enchantress, without a dispel or a Black King Bar.
Sven
* Sven is very vulnerable to chain stun such as Lion, Shadow Shaman or Magnus.
Sven
* Sven has no easy way to burn 
Refraction charges and needs help from teammates to kill TA successfully.
Naga Siren
* Heroes whose attacks can affect multiple enemies at once will clear Naga Siren's illusions. Such heroes include Sven, Magnus, Dragon Knight, Luna, Medusa, Templar Assassin, Gyrocopter, Muerta.
Naga Siren
* Ensnare disables Templar Assassin's invisibility and Blink Dagger (a core item on Templar Assassin), and her illusions will break Refraction easily.
Sven
* Heroes with naturally low mana can be easily shut down by E.M.P.: Sven, 
Tiny, 
Wraith King, 
Omniknight
Naga Siren
* Heroes with AoE nukes will clear her illusions in no time, especially if they are percentage-damage-based, like Underlord's 
Firestorm, 
Elder Titan's 
Earth Splitter, Enigma's 
Midnight Pulse, 
Zeus's 
Arc Lightning, Jakiro's 
Liquid Frost from Aghanim's Shard etc.
Sven
* Melee heroes that get kited easily have hard times dealing with Puck without any lockdowns, as Puck is one of the most mobile heroes. Heroes like Sven, Lifestealer, 
Ursa and 
Alchemist may have problems to get to Puck without proper initiation items. They also lack reliable lockdowns, as their disables are easily avoidable for Puck, or are just a soft disable.
Naga Siren
* Heroes with long-lasting, undispellable debuffs will pinpoint the true Naga Siren: 
Spirit Breaker, Bloodseeker, 
Witch Doctor.
Naga Siren
* Heroes with long-lasting, undispellable debuffs will pinpoint the true Naga Siren: Spirit Breaker, Bloodseeker, Witch Doctor.
Naga Siren
* Heroes who are reliant on illusions or summons: Chaos Knight, 
Broodmother, Naga Siren.
Sven
* Heroes who thrive on teamfights can be a problem, such as Venomancer, Necrophos, Centaur Warrunner...
Naga Siren
* Heroes that heavily depend on illusions or summons, (Naga Siren, Terrorblade, Phantom Lancer, 
Lycan,...) are vulnerable to Sleight of Fist and even more so if Ember Spirit has 
Battle Fury.
Sven
* Heroes that lose a great amount of damage output and become less threatening: Phantom Assassin, Sven, Slark, Phantom Lancer.
* Once you have an Aghanim's Scepter, Shadow Demon instantly reaches a new power spike and becomes a counter for a variety of heroes that have strong passives.
* Heroes that lose a great amount of their tankiness and become easier to finish off: Bristleback, Spectre, Phantom Assassin, Enchantress, Dragon Knight.
* Heroes that lose a great amount of damage output and become less threatening: Phantom Assassin, Sven, Slark, Phantom Lancer.
* You can always stack camps and farm the scepter with Shadow Poison.
Naga Siren
* Since Naga Siren is a hero who barely goes for Black King Bar, she is vulnerable to nukers with strong magical damage and big area-of-effect spells in every game more than any other carry heroes: 
Sand King, Jakiro, Leshrac, 
Lina, 
Earthshaker, Zeus.
Sven
* Heroes that rely on right-clicks will find themselves unable to damage opponents seriously after being affected by Static Link, like Sven, Bloodseeker, and Juggernaut.
Additional:
* 
Static Link saps Sven's insane attack damage, and goes through Black King Bar.
Naga Siren
* Zeus's abilities deal high amounts of burst magical damage, which ignores Naga Siren's high armor.
* Arc Lightning is a good way to destroy Naga Siren's illusions due to it's capabilities to bounce between enemies.
* 
Static Field from Aghanim's Shard can automatically hit everything in a big radius, taking a huge chunk of health out of Naga Siren's illusions, regardless of how much health they have.
Sven
* Heroes who cannot prevent Sven from killing supports will always be at a disadvantage in fights such as Lina, Slark and Zeus.
Sven
* 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.
Naga Siren
* 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.
Sven
* 
Cloak and Dagger makes Sven unable to detect where Riki is until he shows or his team provides detection.
* 
Smoke Screen will make Sven miss attacks before he has his Black King Bar.
Naga Siren
* Ensnare prevents using any kind of movement abiilties, Making Naga Siren good against heroes who rely on gap-closing abilities to escape: Phantom Assassin, Magnus, Slark, Riki, 
Faceless Void, 
Storm Spirit.
Sven
* Heroes who are entirely reliant on dealing physical damage and/or have very little to no area-of-effect abilities will make Underlord tickle and will have no effect against him thanks to his 
Atrophy Aura, and will also be unable to ambush Underlord and his team if Underlord chooses to use 
Fiend's Gate to get to a designated point of the map: Phantom Assassin, Terrorblade, Troll Warlord, 
Drow Ranger, Phantom Lancer, Chaos Knight, Sven, Wraith King, 
Bounty Hunter, Alchemist, Templar Assassin, 
Nyx Assassin, Bane.
Naga Siren
* Atrophy Aura makes it hard or Naga Siren to farm on lane and damage Underlord with 
Rip Tide in teamfights. And her only way to counter this is by playing Nuker role.
* Firestorm is very useful for clearing Naga Siren's illusions from Mirror Image and Manta Style.
* However, Naga Siren can catch Underlord and his team unprepared with Song of the Siren if he chooses to use Fiend's Gate to get to a designated point of the map. Naga Siren can also prevent escaping with Fiend's Gate with Ensnare and Reel In from Aghanim's Scepter.
Additional:
* Atrophy Aura makes it hard or Naga Siren to farm on lane and damage Underlord with Rip Tide in teamfights. And her only way to counter this is by playing Nuker role.
* Firestorm is very useful for clearing Naga Siren's illusions from Mirror Image and Manta Style.
* However, Naga Siren can catch Underlord and his team unprepared with Song of the Siren if he chooses to use Fiend's Gate to get to a designated point of the map. Naga Siren can also prevent escaping with Fiend's Gate with Ensnare and Reel In from Aghanim's Scepter.
Sven
* Strong laners are usually at a disadvantage because of how well Sven can jungle. Heroes such as 
Dark Seer. Underlord and 
Legion Commander may find that later Sven takes care of them very quickly after some jungle farming.
Naga Siren
* Heroes with strong area-of-effect damaging and/or disabling abilities will be able to intercept Underlord and his team when they exit from Fiend's Gate: Luna's Aghanim's Scepter upgraded 
Eclipse, Dawnbreaker's Solar Guardian, Axe's Berserker's Call, 
Mars's 
Arena of Blood, Jakiro's Macropyre, 
Dual Breath and 
Ice Path, Naga Siren's Song of the Siren, 
Razor's 
Eye of the Storm and 
Plasma Field, Lina's 
Light Strike Array, Broodmother's 
Spinner's Snare from Aghanim's Scepter, Elder Titan's Earth Splitter and 
Echo Stomp, Alchemist's 
Unstable Concoction and 
Acid Spray, 
Queen of Pain's 
Sonic Wave, Dark Seer's 
Wall of Replica and 
Vacuum, Venomancer's 
Noxious Plague and 
Poison Nova from Aghanim's Scepter, Oracle's 
Fortune's End and 
Rain of Destiny from Aghanim's Shard, Bloodseeker's 
Blood Rite, Enigma's Black Hole and Midnight Pulse, 
Shadow Fiend's 
Requiem of Souls, Batrider's Aghanim's Scepter upgraded Flaming Lasso, Firefly, Flamebreak and Sticky Napalm, 
Ancient Apparition's 
Ice Blast, Sand King's 
Epicenter, 
Sand Storm and 
Burrowstrike, Gyrocopter's Call Down, 
Ember Spirit's 
Sleight of Fist, 
Death Prophet's 
Exorcism and 
Silence, 
Monkey King's 
Wukong's Command, 
Crystal Maiden's 
Freezing Field, Muerta's 
The Calling, Medusa's Stone Gaze, Zeus's 
Nimbus from Aghanim's Scepter. 
Dark Willow's 
Bramble Maze, 
Pangolier's 
Swashbuckle, Grimstroke's Soulbind, 
Ink Swell and 
Stroke of Fate, Earthshaker's Echo Slam and 
Fissure, 
Puck's 
Dream Coil and 
Waning Rift, 
Winter Wyvern's Winter's Curse, Magnus's Reverse Polarity.
Sven
* Other heroes that rely on physical attacks to deal damage and not their abilities: Troll Warlord, 
Sniper, Monkey King, Sven.
Naga Siren
* As long as Windranger is able to identify the real hero among the illusions, heroes relying on them can be easily tagged with Focus Fire: Chaos Knight, Terrorblade, Phantom Lancer, Naga Siren.
Sven
* Sven with Aghanim's Scepter-upgraded Storm Hammer can easily chase down Windranger and dispel her Windrun at the same time.
Sven
* Storm Hammer locks down Chen and his converted creeps.
* Great Cleave and God's Strength can destroy Chen and his creeps quickly.
* Warcry minimizes damage taken from creeps's attacks.
Additional:
* Great Cleave can quickly destroy Chen's creeps in team fights, before they have a chance to do much.
Naga Siren
* Naga Siren can make landing Chen's combo very hard due to her being an illusion hero thanks to Mirror Image.
* Rip Tide can deal big damage to Chen and reduce Chen's armor, as well as easily kill all of Chen's creeps.
* Naga Siren often builds 
Radiance, which allows her to quickly clear Chen's creeps.
* Ensnare will prevent Chen from escaping.
* With Aghanim's Scepter, Naga Siren can get access to Reel In, which can separate Chen from his creeps and draw him closer to Naga Siren and her team to finish her off. To make things worse, Chen has no way to cancel Reel In on his own, and must rely on outside from {U:Centaur Conqueror} or {U:Mud Golem} under his control.
* Carry or Nuker Naga Siren can often finish off Support Chen before he can have a chance to activate 
Hand of God.
Additional:
* Naga Siren can make landing Chen's combo very hard due to her being an illusion hero.
* Rip Tide can deal big damage to Chen and reduce Chen's armor, as well as easily kill all of Chen's creeps.
* Naga Siren often builds Radiance, which allows her to quickly clear Chen's creeps.
* Ensnare will prevent Chen from escaping.
* With Aghanim's Scepter, Naga Siren can get access to Reel In, which can separate Chen from his creeps and draw him closer to Naga Siren and her team to finish her off. To make things worse, Chen has no way to cancel Reel In on his own, and must rely on outside from {U:Centaur Conqueror} or {U:Mud Golem} under his control.
* Carry or Nuker Naga Siren can often finish off Support Chen before he can have a chance to activate Hand of God.
Sven
* Great Cleave with God's Strength clears Terrorblade's illusions quickly.
* Storm Hammer's AoE stuns Terrorblade and his illusions.
* Warcry gives Sven and his allies armor to withstand Terrorblade's only-physical damage output.
Naga Siren
* Naga Siren can very easily dispel the 
Reflection with Mirror Image. And Besides Reflection that can be used to detect real Naga Siren, Terrorblade has no other ways to deal with Naga Siren's illusions. And what's worse is that Naga Siren can much easily detect the real Terrorblade due to 
Conjure Image having illusions having different colors. In addition, Terroblade is not a common Battle Fury nor Mjollnir wielder to counter this problem.
* Aghanim's Scepter upgraded Ensnare will allow Naga Siren to root Terrorblade even ithrough Black King Bar. And with Aghanim's Scepter, Naga Siren can get access to 
Reel In ability, which can allow her to pull Terrorblade toward herself and her team and away from his illusions, even through Black King Bar.
* Naga Siren can rapidly damage Terrorrblade and weaken Terrorblade's armor with Rip Tide, which combined with Terrorblade's low health and strength gain can almost completely discourage Terrorblade from even being present in teamfights. Rip Tide can also weaken armor of Terrorblade's illusions and damage them.
* Song of the Siren can be used to save an ally whom Terrorblade has used 
Sunder under the condition Naga Siren is quick enough to do it. And since Terrorblade has no "real" burst damage potential outside from Sunder, Naga Siren will usually have plenty of time to save an allied hero on which Sunder was used. Aghanim's Shard upgraded Song of the Siren can also heal her allies around her for it's duration, which allows Naga Siren to nullify effects of Sunder.
* However, Naga Siren's lack of burst damage can make it difficult for her to burst down Terrorblade before he can use Sunder unless Naga Siren has either Black King Bar or Linken's Sphere to protect herself against it or if she is played as Nuker.
Additional:
* Naga Siren can very easily dispel the Reflection with Mirror Image. And Besides Reflection that can be used to detect real Naga Siren, Terrorblade has no other ways to deal with Naga Siren's illusions. And what's worse is that Naga Siren can much easily detect the real Terrorblade due to Conjure Image having illusions having different colors. In addition, Terroblade is not a common Battle Fury nor Mjollnir wielder to counter this problem.
* Aghanim's Scepter upgraded Ensnare will allow Naga Siren to root Terrorblade even through Black King Bar. And with Aghanim's Scepter, Naga Siren can get access to Reel In ability, which can allow her to pull Terrorblade toward herself and her team and away from his illusions, even through Black King Bar.
* Naga Siren can rapidly damage Terrorrblade and weaken Terrorblade's armor with Rip Tide, which combined with Terrorblade's low health and strength gain can almost completely discourage Terrorblade from even being present in teamfights. Rip Tide can also weaken armor of Terrorblade's illusions and damage them.
* Song of the Siren can be used to save an ally whom Terrorblade has used Sunder under the condition Naga Siren is quick enough to do it. And since Terrorblade has no "real" burst damage potential outside from Sunder, Naga Siren will usually have plenty of time to save an allied hero on which Sunder was used. Aghanim's Shard upgraded Song of the Siren can also heal her allies around her for it's duration, which allows Naga Siren to nullify effects of Sunder.
* However, Naga Siren's lack of burst damage can make it difficult for her to burst down Terrorblade before he can use Sunder unless Naga Siren has either Black King Bar or Linken's Sphere to protect herself against it or if she is played as Nuker.
Sven
* Great Cleave will kill Lycan's summons very rapidly.
* Warcry will allow Sven and his allies to tank Lycan's damage, which is mainly physical.
* Storm Hammer will damage and stun Lycan's as well as his summons.
Naga Siren
* Lycan is a hero focused entirely on single target physical damage and lacks disables or AoE damage. Due to this, he will have difficulties dealing with illusions or Naga Siren's Ensnare.
Sven
* Warcry makes it difficult to burst Sven down with both the passive (with Aghanim's Shard) and active component.
* Sven under the effect of God's Strength and his massive physical damage make Sven very dangerous to engage in the mid game.
Naga Siren
* Mirror Image can be effective since Night Stalker cannot withstand fighting illusions. If he's unable to tell which Naga Siren is real, he will have a hard time landing his 
Void. However, if Night Stalker obtains an Aghanim's Scepter, the upgraded Void will hit and may even locate the real Naga Siren in fights.
Additional:
* Ensnare and Song of the Siren prevents Night Stalker from escaping and ganking during daytime or even nighttime.
* Rip Tide reduces Night Stalker's armor, making him easier to focus down.
* Mirror Image can be effective against Night Stalker, due to his single target abilities.
Sven
* Storm Hammer's faster projectile speed and cast time allows Sven to stun Chaos Knight and his illusions before he can cast Chaos Bolt.
* Warcry's armor bonus counteracts Reality Rift's debuff and reduces Chaos Knight's damage output.
* Great Cleave and God's Strength devastates Phantasm illusions.
Additional:
* Great Cleave is very effective against Chaos Knight's illusions.
* Storm Hammer's radius can catch all of Chaos Knight's illusions at once, especially after 
Reality Rift.
* Warcry shields Sven and his teammates against Chaos Knight's physical damage output.
Naga Siren
* Illusion-based and multi-unit heroes can take advantage of Chaos Knight's lack of area damage: Naga Siren, Phantom Lancer, Broodmother
Sven
* Fragile supports who die in a few hits against Sven's high physical damage: Crystal Maiden, 
Vengeful Spirit, Dark Willow.
Naga Siren
* Mirror Image can dispel Frostbite. A similar effect can be achieved with Manta Style, a core item on Naga Siren.
* Song of the Siren can stop Freezing Field regardless of any kind of invisibility as well as allow Naga Siren's team to quickly close the gap on Crystal Maiden.
* With Aghanim's Scepter, Naga Siren can get access to Reel In ability, which can allow her to pull Crystal Maiden toward herself and her team and cancel Freezing Field even through Black King Bar.
Additional:
* Mirror Image can dispel Frostbite.
* Song of the Siren can stop Freezing Field regardless of any kind of invisibility as well as allow Naga Siren's team to quickly close the gap on Crystal Maiden.
* Ensnare allows Naga Siren and her team to quickly catch up with Crystal Maiden and kill her.
* With Aghanim's Scepter, Naga Siren can get access to Reel In ability , which can allow her to pull Crystal Maiden toward herself and her team and cancel Freezing Field even through Black King Bar.
Sven
* Melee carries who usually buy an early Black King Bar, and have gap closing abilities can be good against the Arc Warden, such as Slark, Riki, Earthshaker with Aghanim's Scepter, Sven with Aghanim's Scepter etc.
Naga Siren
* Naga Siren's illusions from Mirror Image can depush the lanes pushed by the Tempest Double, relieving the pressure.
* Mirror Image can dispel Flux, and the illusions can stop Flux from working to it's full power.
Additional:
* Song of the Siren stops Arc Warden from acting and allows Naga Siren's team to close in on him, past his 
Magnetic Field.
* Mirror Image dispels 
Flux. The illusions created from it also disable the slow from Flux if Arc Warden casts it after Mirror Image.
* Arc Warden's playstyle heavily favors split-pushing, which Naga Siren can compete against with her illusions.
Sven
* Special mention to Sven as he may not be able to get close, but if he does, God's Strength will make very short work of Sniper.
Sven
* Past the early game, Sniper is an easy target for Sven to jump on with Aghanim's Scepter upgraded Storm Hammer, Blink Dagger, 
Silver Edge or 
Harpoon, common items on Sven.
* Sven's high armor and health pool makes it difficult for Sniper to focus, as his main source of damage is his right click, especially if Sven uses Warcry.
* Sniper is very squishy, and will not stand a chance against Sven head on.
Naga Siren
* Ensnare with her attacks allows Naga Siren to gank Sniper easily.
* Rip Tide removes Sniper's very little armor.
Naga Siren
* Heroes who rely on illusions will see them destroyed easily by Overwhelming Odds: Phantom Lancer, Chaos Knight, Terrorblade, Naga Siren
Sven
* 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.
Naga Siren
* Song of the Siren lasts long enough to prevent a successful 
Duel (but only if Naga wasn't the target).
Sven
* Heroes who cannot prevent Sven from killing towers will often struggle from a small map very early, such as Phantom Assassin, Storm Spirit and Phantom Lancer.
Naga Siren
* Ensnare prevents using any kind of movement abiilties, Making Naga Siren good against heroes who rely on gap-closing abilities to escape: Phantom Assassin, Magnus, Slark, Riki, Faceless Void, Storm Spirit.
Sven
* Heroes who cannot prevent Sven from killing towers will often struggle from a small map very early, such as Phantom Assassin, Storm Spirit and Phantom Lancer.
Naga Siren
* Ensnare prevents using any kind of movement abiilties, Making Naga Siren good against heroes who rely on gap-closing abilities to escape: Phantom Assassin, Magnus, Slark, Riki, Faceless Void, Storm Spirit.
Sven
* Heroes who cannot prevent Sven from killing supports will always be at a disadvantage in fights such as Lina, Slark and Zeus.
Naga Siren
* Ensnare prevents using any kind of movement abiilties, Making Naga Siren good against heroes who rely on gap-closing abilities to escape: Phantom Assassin, Magnus, Slark, Riki, Faceless Void, Storm Spirit.
Sven
* 
Doom generally does not impede Sven in almost any way, provided he has activated God's Strength beforehand.
Sven
* Great Cleave and God's Strength destroys illusions in just a few hits.
* Storm Hammer's AoE stun will hit Phantom Lancer when he's grouped up with illusions.
* Sven's low mana causes him to take less damage from Diffusal Blade. This is further reduced by the armor bonus from Warcry.
Additional:
* Great Cleave and God's Strength cuts through Phantom Lancer's illusions in no time.
* Storm Hammer's AoE stun will hit Phantom Lancer and his illusions.
Sven
* Sprout is good for trapping melee carries with no escape abilities: Sven, Alchemist, Lifestealer etc.
Sven
* Heroes with cleave damage: Sven, Magnus, 
Kunkka.
Naga Siren
* Naga Siren is a natural split-pusher. With Rip Tide, she will easily out-push Nature's Prophet, farming his treants in the process.
* Ensnare prevents 
Teleportation. Even if he hides inside 
Sprout, Song of the Siren lasts long enough to prevent him from escaping.
Additional:
* Naga Siren is a natural split-pusher. With a Radiance equipped, she will easily keep the lanes pushed out, therefore keeping backdoor protection enabled and preventing Nature's Prophet from dealing building damage.
* Ensnare can prevent Teleportation. Aghanim's Scepter upgraded Ensnare can also affect Nature's Prophet even if he is spell immune. And Reel In from Aghanim's Scepter can also be used to separate Nature's Prophet from his treant and bring him close to Naga Siren and her team to burst him down.
* Song of the Siren will stop Nature's Prophet from escaping even if he has hidden inside of Sprout. Aghanim's Shard upgraded Song of the Siren can also heal her allies and save them from Nature's Prophet.
Naga Siren
* Song of the Siren is very difficult for Rubick to 
Spell Steal when he is affected by sleep.
* Ensnare and Rip Tide together with some attacks can take Rubick down quickly, due to his low health pool and armor.
* Naga Siren usually buys Diffusal Blade, which may prevent Rubick from using his abilities.
* Mirror Image allows Naga Siren to dodge the incoming stun from 
Telekinesis (when she is not a target), and it can also dispel 
Fade Bolt's damage reduction debuff.
Sven
* God's Strength allows Sven to take down Death Prophet quickly, reducing the damage dealt over time from Exorcism.
* Warcry's bonus armor and movement speed is very useful for Sven and his teammates against Exorcism, which deals physical damage.
Sven
* With God's Strength, Warlock's Golem from 
Chaotic Offering will go down in a matter of seconds. The two weaker golems granted by Aghanim's Scepter will fare worse due to Great Cleave hitting both.
* Aghanim's Scepter upgraded Storm Hammer Aghanim's Scepter can dispel 
Shadow Word.
Additional:
* God's Strength combined with Great Cleave destroys Chaotic Offering golems within seconds.
* Warcry gives Sven and his allies armor to help against Warlock's Golem's heavy physical damage and movement speed to help escape Upheaval.
* Storm Hammer disrupts Upheaval.
Sven
* 
Purification can heal allies while dealing pure damage to Sven.
* 
Heavenly Grace can remove Storm Hammer's debuff immediately or make it a very mediocre stun.
* 
Guardian Angel negates Sven's massive damage during God's Strength.
* It should also be noted Sven can remove Omniknight's active spells with Aghanim's Scepter.
Sven
* Although Sven relies often on physical damage, an Aghanim's Scepter upgraded Storm Hammer can dispel Guardian Angel with its wide radius.
Naga Siren
* Even though Naga Siren relies on direct attacks to deal damage for most of the time, Song of the Siren allows her to easily waste Guardian Angel.
* Ensnare fully works on targets affected with Heavenly Grace. However, Ensnare is dispellable with any dispel, and so can be dispelled by Heavenly Grace.
* As an agility hero that relies on illusions, Naga Siren is one of the most natural Diffusal Blade carriers, the bane of every hero with a small mana pool. Naga Siren can also buy items that deal magical damage like Radiance, 
Dagon, 
Ethereal Blade, 
Revenant's Brooch, 
Veil of Discord and 
Gleipnir to attack Omniknight's allies protected with Guardian Angel.
Additional:
* Although Naga Siren relies mostly on physical damage, Song of the Siren can be used to time out Guardian Angel, giving Naga Siren's team an easy opportunity to counter-initiate.
* Radiance allows it's owner to deal magical damage to multiple enemy heroes at once, and since Naga Siren often buys it, Guardian Angel is not a very good ability for protection against Naga Siren.
* Likewise, Nuker build Naga Siren (which primarly consists of items such as Radiance, Ethereal Blade, Dagon and Veil of Discord) can render Guardian Angel useless. Although Nuker is not a role Naga Siren should be playing.
Sven
* Great Cleave cleans up Spiderlings quicker than most spells, as it ignores their magic resistance.
* Sven is a natural Black King Bar carrier, protecting him from Silken Bola, Spawn Spiderlings and 
Orchid Malevolence.
* Warcry and God's Strength allow Sven to easily out-damage Broodmother.
Additional:
* Great Cleave can clear Spiderlings very quickly, and give Sven lot of gold.
* Warcry shields Sven and his allies against Broodmother and her Spiderlings.
Naga Siren
* Song of the Siren completely wastes Abaddon 
Borrowed Time while keeping him in place.
* Naga Siren is able to simply dispel Abaddon's 
Curse of Avernus with Mirror Image before getting hit 4 times consecutively.
* Although Naga Siren's illusions can be easily destroyed by 
Aphotic Shield, Naga Siren can resolve that issue easily by purchasing 
Heart of Tarrasque to drastically increase her durability. Plus, the said item makes Naga Siren harder to be distinguished from her illusions.
Naga Siren
* Ensnare and Song of the Siren can be used to cancel both, 
Tether and 
Relocate and to close the distance on Io.
* Rip Tide combined with illusions from Mirror Image often finish off Io before he can save himself with Tether or Relocate.
* 
Spirits's weak area-of-effect makes it a bad tool to deal with Naga Siren's illusions from Mirror Image.
* Once Naga Siren buys Aghanim's Scepter, she can gain access to Reel In, which not only allows her to cancel both, Tether and Relocate, but also to pull Io to herself and her team while he is affected with Ensnare, similarly to Batrider's Flaming Lasso.
* Aghanim's Shard upgraded Song of the Siren can also heal the hero Io and his Tethered targed try to gank.
Additional:
* Ensnare and Song of the Siren can be used to cancel both, Tether and Relocate and to close the distance on Io.
* Rip Tide combined with illusions from Mirror Image often finish off Io before he can save himself.
* Spirit's weak area-of-effect makes it a bad tool to deal with Naga Siren's illusions from Mirror Image.
* Once Naga Siren buys Aghanim's Scepter, she can gain access to Reel In, which not only allows her to cancel both, Tether and Relocate, but also to pull Io to herself and her team while he is affected with Ensnare, similarly to Batrider's Flaming Lasso.
* Aghanim's Shard upgraded Song of the Siren can also heal the hero Io and his tethered targed try to gank.
Naga Siren
* Heroes with summons like Broodmother, Enigma, Nature's Prophet; or illusions, like Naga Siren, Terrorblade are effective at keeping the choke points and rune spawns safe from Proximity Mines.
Sven
* Late game heroes are Sven's favourite kind of opponent, such as Anti-Mage, Spectre and Shadow Fiend.
Naga Siren
* Ensnare prevents using any kind of movement abiilties, Making Naga Siren good against heroes who rely on gap-closing abilities to escape: Phantom Assassin, Magnus, Slark, Riki, Faceless Void, Storm Spirit.
Sven
* Generally heroes who don't rely on magical damage, such as Sven, Phantom Assassin, and 
Outworld Destroyer, as they can practically ignore Flesh Heap's damage block.
Sven
* Side lanes with disables will greatly reduce the likeliness Void Spirit will be willing to rotate: Sven, Tiny, Wraith King, 
Ogre Magi.
Sven
* Heroes with high burst damage and Black King Bar can take down Dark Willow quickly: Phantom Assassin, Sven, Wraith King
Sven
* Late game heroes are Sven's favourite kind of opponent, such as Anti-Mage, Spectre and Shadow Fiend.
Sven
* Heroes who struggle to fight back against Sven at any point in the game are at a severe disadvantage: Alchemist, Anti-Mage, Crystal Maiden.
Naga Siren
* Nyx Assassin's skillset is mostly single-targeted, therefore he will have difficulties against heroes with illusions and summons: Naga Siren, Broodmother, Lycan, 
Visage, Phantom Lancer. And to make things worse, Nyx Asassin is not a common Battle Fury, 
Maelstrom, Mjollnir, Gleipnir or Radiance wielder to counter this problem.
Naga Siren
* Illusion heroes like the aforementioned Phantom Lancer or Naga Siren, or heroes that tend to buy Manta Style, like Luna or Juggernaut, will give Slardar a hard time, as his damage is single-targeted.
Sven
* Sven's Great Cleave can clear Anti-Mage's illusions from Manta Style and his high health pool and low mana, making Mana Void very ineffective, although keep in mind that Storm Hammer is extremely easy to reflect with a well-timed Counterspell.
Additional:
* Anti-Mage is fairly fragile, and cannot stand against Sven in a prolonged fight.
* Sven's Black King Bar and low base mana can protect Sven from the effects of 
Mana Break and 
Mana Void.
* Great Cleave destroys the illusions from Anti-Mage's Manta Style.
* Although Sven should be careful as a well-timed 
Counterspell can block and reflect Storm Hammer back at Sven.
Naga Siren
* Heroes with illusions and summons can swarm and overwhelm Bane, who has no area abilities to deal with them outside from Aghanim's Shard upgraded 
Brain Sap: Broodmother, Chaos Knight, Naga Siren, Nature's Prophet, Phantom Lancer, Terrorblade, Visage, 
Warlock, Wraith King.
Naga Siren
* Naga Siren with Mirror Image
* Heroes that can dodge Glimpse:
* Puck with 
Phase Shift
* Riki with 
Tricks of the Trade
* Phantom Lancer with 
Doppelganger
* Ember Spirit with Sleight of Fist and 
Activate Fire Remnant
* Chaos Knight with 
Phantasm
* Naga Siren with Mirror Image
* 
Tusk with 
Snowball
* Juggernaut with 
Omnislash
* 
Brewmaster with 
Primal Split
* Lifestealer with 
Infest
* 
Phoenix with 
Supernova
Naga Siren
* Illusion heroes, such as Naga Siren, Phantom Lancer, Chaos Knight, Terrorblade will become strong against Tinker in the late game. Without Aghanim's Scepter Tinker is forced to defensively disarm heroes with Laser, leaving illusions free to deal physical damage which Tinker's low armor makes highly effective. In addition, Mjollnir or Battle Fury, two common pickups against illusion heroes, don't work well on Tinker at all.
Naga Siren
* Heroes with illusions: Chaos Knight, Naga Siren, Phantom Lancer, Terrorblade
Naga Siren
* Heroes with summons and illusions such as Broodmother and Naga Siren, are ill-suited for Wraith King to fight, as he has no source of waveclear.
Naga Siren
* Heroes with summons and illusions can find themselves easily bested by Lina, like Broodmother, Nature's Prophet, 
Chen, Terrorblade, Naga Siren, Visage, Wraith King, Lycan, Phantom Lancer, Shadow Shaman.
Sven
* Sven has a high health pool and is a natural Black King Bar holder and is very hard to kill for Lina.
* Sven also has high physical damage, making it easy for him to burst her down.
Sven
* Heroes who rely on burst physical damage are affected by Lucky Shot's disarm: Terrorblade, Sven, 
Clinkz, 
Windranger, Alchemist, Dragon Knight, Legion Commander
Naga Siren
* Heroes who are illusion based, or even heroes who frequently build Manta Style can be cleared quickly by Pangolier's high damage, or lose their damage ouput because of Lucky Shot: Chaos Knight, Naga Siren
Sven
* Warcry can protect Sven and his teammates from Swashbuckle.
* With Black King Bar, Sven will be able to protect himself from most of Pangolier's skills.
Naga Siren
* Heroes with powerful rooting abilities will disable most of Pangolier's skills, a bonus point if it pierces spell immunity since it will also be able to stop Pangolier during his Rolling Thunder: 
Treant Protector, 
Meepo, Crystal Maiden, Dark Willow, Underlord, Naga Siren
Sven
* Melee heroes with low mobility can be kited and killed by Viper: Treant Protector, Kunkka, Alchemist, Troll Warlord, Wraith King, Tiny, Sven.
Naga Siren
* Naga Siren can easily disjoint, and dispel 
Corrosive Skin with Mirror Image.
* Since Viper is mostly a single-target hero, he will not have almost any chance against Naga Siren because she is an illusion based hero.
* Viper has no burst damage, so Naga Siren will have plenty of time to use Aghanim's Shard upgraded Song of the Siren heal her allies before Viper can finish them off.
Naga Siren
* Sand King and Phoenix have many tools to deal with multiple enemies at once, which will work well against a crowd of illusions.
Naga Siren
* Song of the Siren does not affect Supernova, which allows her and her team to focus the egg while the enemy team is affected by sleep.
* Phoenix cannot use 
Icarus Dive for escaping when rooted by Ensnare.
* However, Phoenix has many area-of-effect abilities that allow him to clear Naga Siren's illusions from Mirror Image.
Sven
* Heroes who can fight back easily are not ideal matchups for Sven, such as Troll Warlord as mentioned above, 
Lone Druid and Templar Assassin.
Naga Siren
* Unless Lone Druid purchases a Black King Bar for his Spirit Bear, Ensnare will easily kite the Spirit Bear.
* Song of the Siren allows Naga Siren and her team to completely bypass the Spirit Bear and hunt for the Lone Druid himself when starting a fight.
* Lone Druid's lack of innate AoE capabilities mean that Naga Siren's illusions have no problem against him.
Sven
* Heroes who can take advantage of God's Strength being on cooldown are also not great matchups, such as Templar Assassin, Morphling and Huskar.
Naga Siren
* Mirror Image can cause Huskar to Life Break the wrong target.
* Rip Tide reduces Huskar's already low armor.
* Song of the Siren allows teams to recover from Huskar's initiation, as well as the damage over time from Burning Spears.
Naga Siren
* Heroes with AoE nukes will clear her illusions in no time, especially if they are percentage-damage-based, like Underlord's Firestorm, Elder Titan's Earth Splitter, Enigma's Midnight Pulse, Zeus's Arc Lightning, Jakiro's Liquid Frost from Aghanim's Shard etc.
Sven
* Storm Hammer interrupts Echo Stomp.
Naga Siren
* Naga Siren's Song of the Siren may be useful but Poof will destroy all of her illusions.
Sven
* Great Cleave and God's Strength can take down Meepo and his clones very quickly.
* The lack of spell immunity for Meepo's clones makes them vulnerable to Storm Hammer.
Additional:
* Great Cleave will devastate Meepo's clones. Against a closely packed group, Sven does not even need to target the clone with the lowest health.
Naga Siren
* Luna's 
Moon Glaives and 
Lunar Blessing can clear waves of Naga Siren's illusions from Mirror Image.
* Once Naga Siren's illusions are cleared with Aghanim's Shard upgraded Moon Glaives, Eclipse can often finish off Naga Siren before she can escape with Song of the Siren.
* A well-timed Aghanim's Scepter upgraded Eclipse combined with 0.25 Eclipse Lucent Ministun talent can be casted at long range and allow Luna to burst down Naga Siren faster and repetively stun Naga Siren, preventing her from escaping with Song of the Siren and 
Town Portal Scroll without getting caught in it's range.
* Luna is a natural Black King Bar wielder unlike Naga Siren who barely goes for it, which allows Luna to freely attack Naga Siren during Song of the Siren and potentially get rid of the most of the damage and crowd-control from Naga Siren.
Additional:
* Luna's Moon Glaives and Lunar Blessing can clear waves of Naga Siren's illusions from Mirror Image, especially when combined with Gleipnir and Manta Style. Aghanim's Shard upgraded Moon Glaives can also be used to destroy Naga Siren's illusions and damage the real Naga Siren if they are too close to Luna while also reducing any damage Naga Siren inflicts on Luna for their duration.
* Once Naga Siren's illusions are cleared, Eclipse can often finish off Naga Siren before she can escape with Song of the Siren.
* A well-timed Aghanim's Scepter upgraded Eclipse combined with 0.25 Eclipse Lucent Ministun talent can be casted at long range and allow Luna to burst down Naga Siren faster and repetively stun Naga Siren, preventing her from escaping with Song of the Siren and Town Portal Scroll without getting caught in it's range.
* Luna is a natural Black King Bar wielder unlike Naga Siren who barely goes for it, which allows Luna to freely attack Naga Siren during Song of the Siren and potentially get rid of the most of the damage and crowd-control from Naga Siren.
Sven
* A couple of nukers and disablers on the same lane can finish a squishy Luna efficiently despite a teammate's assistance: Sven + Shadow Shaman.
Naga Siren
* Heroes that create illusions: Spectre, 
Shadow Demon, Phantom Lancer, Naga Siren, Chaos Knight, Terrorblade) or bring other units into the fight (such as Nature's Prophet, Lone Druid, Chen, Enchantress, Meepo and 
Arc Warden) can cause Eclipse to strike the illusions/summons unintentionally. However, in many cases Moon Glaives can resolve this issue and eliminate them before activating Eclipse, but that will require lots of farming for right-click items.
Naga Siren
* 
Blade Fury offers good AoE damage to clear illusions and can hurt the real Naga Siren as well if she chooses to blend in the illusions. Diffusal Blade does nothing to Juggernaut either when he uses Blade Fury.
* Aghanim's Shard upgraded Blade Fury along with Lv 20 DPS talent will shred all illusions almost instantly, especially when combined with Mjollnir, a common item for Juggernaut.
Sven
* Heroes with high armor and/or durability can handle Juggernaut's ultimate, such as Sven and Dragon Knight.
Additional:
* Warcry allows Sven to tank the damage from Omnislash due to its high armor gain.
* However Blade Fury provides spell immunity which blocks the stun from Storm Hammer.
Naga Siren
* Illusion-based heroes are effective against Omnislash and Juggernaut's single-targeted damage: Naga Siren, Chaos Knight, Terrorblade,Phantom Lancer.
Naga Siren
* Avalanche and Toss combo makes short work of Mirror Image's illusions.
* Tiny's cleave with Tree Grab and area of effect damage with Tree Volley will easily wipe out illusions.
Sven
* 
Avalanche and 
Toss will never be enough damage to take out Sven in a clean way.
* Tiny is very slow with low armour growth and does not buy items to sustain Sven's damage output.
Naga Siren
* 
Mortimer Kisses can make quick work of Naga Siren's illusions.
* 
Scatterblast and 
Firesnap Cookie's AoE damage are also decent ways to deal with Naga's illusions.
Sven
* Storm Hammer stunned can stops Snapfire's Mortimer Kisses.
Sven
* Sven is very vulnerable to chain stun such as Lion, Shadow Shaman or Magnus.
Naga Siren
* Heroes whose attacks can affect multiple enemies at once will clear Naga Siren's illusions. Such heroes include Sven, Magnus, Dragon Knight, Luna, Medusa, Templar Assassin, Gyrocopter, Muerta.
Sven
* Any hero who can counter-initiate in anticipation without getting caught in Reverse Polarity: Sven, Omniknight, Enigma, Luna, Naga Siren, Mars, Jakiro, Venomancer, Elder Titan, Faceless Void, 
Rubick, Keeper of the Light, 
Pugna, 
Invoker, Spectre, Alchemist, Treant Protector, Lina, Oracle, Zeus, Shadow Shaman, Phoenix, Razor, Huskar, Batrider, Kunkka, 
Tidehunter, Wraith King, Sand King, Medusa, Dawnbreaker.
Naga Siren
* Any hero who can counter-initiate in anticipation without getting caught in Reverse Polarity: Sven, Omniknight, Enigma, Luna, Naga Siren, Mars, Jakiro, Venomancer, Elder Titan, Faceless Void, Rubick, Keeper of the Light, Pugna, Invoker, Spectre, Alchemist, Treant Protector, Lina, Oracle, Zeus, Shadow Shaman, Phoenix, Razor, Huskar, Batrider, Kunkka, Tidehunter, Wraith King, Sand King, Medusa, Dawnbreaker.
Naga Siren
* Heroes with long-lasting, undispellable debuffs will pinpoint the true Naga Siren: Spirit Breaker, Bloodseeker, Witch Doctor.
Naga Siren
* Heroes with summons and illusions as Spirit Breaker has no strong AoE capabilities to deal with them: Chaos Knight, Phantom Lancer, Terrorblade, Naga Siren, Broodmother, Warlock, Visage, Nature's Prophet, Shadow Shaman, Lycan, Wraith King.
Sven
* Heroes that can prevent Sven from farming are very strong against him. Such as Riki and Bounty Hunter with their respective invisibility.
Naga Siren
* Naga Siren with Mirror Image
* 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.
Additional:
* Bounty Hunter is a single target damage dealer, so he will not fare well against Naga Siren. Even though Bounty Hunter can use 
Track on her, Mirror Image will dispel the effect. Ensnare also reveals invisible units while they're rooted, putting Bounty Hunter at a disadvantage.
Naga Siren
* Heroes that rely on illusions typically spawn very strong illusions inside Dark Seer Wall of Replica that he can use against them or their team: Phantom Lancer, Chaos Knight, Naga Siren, Terrorblade.
Sven
* Strong laners are usually at a disadvantage because of how well Sven can jungle. Heroes such as Dark Seer. Underlord and Legion Commander may find that later Sven takes care of them very quickly after some jungle farming.
Naga Siren
* Dazzle can instantly destroy all of Naga Siren's illusions from Mirror Image with Aghanim's Shard upgraded 
Poison Touch used on her or any of her illusions.
Naga Siren
* Mirror Image's illusions can easily walk straight at Dazzle and attack him, due to Dazzle's lack of reliable AoE nukes or disables.
* Ensnare roots Dazzle or his allies, making it harder to stay in range of Dazzle's saving abilities.
* Song of the Siren can be used to initiate a fight with superior positioning, potentially zoning Dazzle's high-impact spells out of the fight.
Sven
* With the exception of Magic Missile (unless the player takes the Level 25 Talent "Magic Missile Pierces Spell Immunity"), all of Vengeful Spirit's spells ignore Spell Immunity. This also makes her good against heroes with built-in Spell Immunity like Lifestealer or Juggernaut or heroes that tend to pick up Black King Bar, like Sven.
Sven
* Fragile supports who die in a few hits against Sven's high physical damage: Crystal Maiden, Vengeful Spirit, Dark Willow.
Sven
*
Berserker's Call prevents Sven from bursting his targets before Axe can interfere. The worst kind of opponent for Sven is one who can stop him from attacking who he wants to, which is exactly what Axe does.
Culling Blade may finish off Sven before he has the chance to lifesteal or run with Warcry.
Blade Mail carrier which will make very short work of a Sven with God's Strength activated.
*
* Axe is a very common
Naga Siren
* Axe will destroy her illusions by proccing
Counter Helix more often due to him being hit by more attacks.