Ursa
* Ursa relies on the Blink-Earthshock combo to slow enemies to burst them, but Windranger can use 
Windrun to escape through Earthshock's duration.
* Windrun and 
Focus Fire can easily allow Windranger to kite Ursa and do good amounts of damage in the process.
Additional:
* Windranger can avoid Ursa's primary source of damage, 
Fury Swipes, by simply using Windrun. The slow from 
Earthshock is also rendered irrelevant by Windrun.
* Focus Fire and Windrun can be used to kite Ursa.
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.
Ursa
* Lion has two low cast point disables (
Hex and 
Earth Spike) to control Ursa before he buys a 
Black King Bar.
* Hex is one of the few abilities that cannot be dispelled even with an 
Aghanim's Scepter upgraded Enrage.
* Lion can control Ursa's low mana pool via 
Mana Drain.
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).
Ursa
* Heroes that rely on slows to get kills: 
Lifestealer, 
Night Stalker, 
Ursa, 
Phantom Assassin, Terrorblade.
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.
Ursa
* Heroes who rely heavily on melee attacks and lack early spell immunity are easily blocked and interrupted by Ink Swell: 
Lycan, Ursa, 
Troll Warlord.
Naga Siren
* Heroes who are reliant on illusions or summons: Chaos Knight, 
Broodmother, Naga Siren.
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.
Ursa
* 
The swarm beetle can waste Ursa's 
Overpower attacks.
* Ursa has no inherent way of disabling a slippery Weaver by preventing him from 
Shukuchiing or 
Time Lapseing away, as the slow from Earthshock is useless against Shukuchi's haste effect.
Additional:
* Earthshock's slow is ignored by Shukuchi.
* Ursa can be kited with Shukuchi and his burst damage will be negated with Time Lapse as long as Weaver survives it.
* The Swarm breaks Ursa's 
Blink Dagger, forcing him to deal with the beetles.
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.
Ursa
* If Ursa uses 
Enrage Brewmaster can use Cyclone to render him harmless during his ultimate.
* Brewmaster has two spells to slow down Ursa, allowing his team to kite around him easily.
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.
Ursa
* Plasma Field can spot an Ursa sneaking into Roshan's pit
* Static Link has a 800 link break distance, meaning Razor can stay close enough to drain Ursa' damage, but not too close to get attacked
* Static Link cannot be dispelled by Enrage
* With Storm Surge, Razor will usually be faster than Ursa in most cases
* Eye of the Storm melts through Ursa's armor
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.
Naga Siren
* 
Flak Cannon and 
Call Down can easily clear Naga Siren's illusions.
Ursa
* Enchant can dispel Overpower.
* Enchant's slow can help kite Ursa in fights and also in lane.
* Enchantress can out harass Ursa in lane by using her long attack range and Untouchable, as well as out sustaining him with Nature's Attendants.
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.
Ursa
* Ursa has no sustained AoE to deal with illusions, it becomes worse since Phantom Lancer can create more illusions in a matter of seconds.
* 
Diffusal Blade can be used to drain Ursa mana. This is a standard item for Phantom Lancer in every match.
* 
Doppelganger applies basic dispel on Phantom Lancer, which will remove the slow from Earthshock. It also resets fights with more illusions, making hard for Ursa to hit the real Phantom Lancer.
* 
Manta Style creates two more illusions and also applies a basic dispel, further complicating the problem for Ursa to deal with.
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.
Ursa
* Primal Roar and the slow from Boars makes kiting Ursa very easy.
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.
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.
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.
Ursa
* With Aghanim's Scepter, Broodmother will gain access to 
Spinner's Snare, which will allow her to create invisible lines on her webs from 
Spin Web that will root, deal damage over time, and reveal enemy heroes if they unwittingly step on them. This allows Broodmother to keep her allies alerted on heroes who rely on invisibility-themed and movement-themed abilities and items to surprise enemy heroes and disrupt ganking attempts of enemy heroes: Phantom Assassin, 
Nyx Assassin, 
Mirana, 
Bounty Hunter, Templar Assassin, 
Riki, 
Spirit Breaker, 
Anti-Mage, 
Tusk, Ursa, 
Nature's Prophet, Enigma, 
Void Spirit, Magnus etc.
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.
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: 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.
Naga Siren
* Naga Siren's Song of the Siren may be useful but Poof will destroy all of her illusions.
Ursa
* Melee carries such as Sven, Ursa or Lifestealer can be slowed and easily kited with Demonic Purge.
Additional:
* Shadow Demon's 
Demonic Purge renders Ursa useless even through Black King Bar as it slows him, continually purges his Overpower charges and can not be dispelled by Ursa's Enrage.
* 
Disruption is a good way to save teammates against Ursa. Disrupting Ursa is also a good way to kite him, as it can not be dispelled by Enrage.
Ursa
* Positioning-reliant heroes (
Windranger, 
Tidehunter, Ursa...), since Earth Spirit can disrupt positioning with his Boulder Smash.
Naga Siren
* Heroes with long-lasting, undispellable debuffs will pinpoint the true Naga Siren: Spirit Breaker, Bloodseeker, Witch Doctor.
Naga Siren
* Illusion heroes will struggle against Primal Beast's area damage capability, such as Chaos Knight, Naga Siren, Terrorblade.
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
Ursa
* 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.
Ursa
* Heroes with evasions: Phantom Assassin, 
Brewmaster, 
Hoodwink, Windranger.
Ursa
* Laser can be cast on a initiating Ursa, normally causing him to waste multiple Overpower attacks, forcing him to either Black King's Bar, or Enrage to protect himself.
* Ursa will probably carry a Linken's Sphere to counter Tinker's Laser. Popping it with Scythe of Vyse is actually preferable, due to Laser's high Pure damage.
* While Ursa is a common Blink Dagger carrier, but he otherwise has no way to close the gap, Baiting him into using his Blink, then blinking away, allows Tinker to easily kite Ursa.
* Enrage is generally how Ursa disengages, Due to Tinker's high maneuverability, he can follow him until it runs out. then burst him down with high magic damage.
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.
Ursa
* Bane can use 
Nightmare and 
Fiend's Grip to lock down Ursa early game and in team fights, forcing Ursa to buy a Black King Bar and making him very vulnerable to being kited once his Black King Bar is down to 6 seconds.
* Overall, Bane's potent disables force Ursa to build more defensive items and play more defensively in general.
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.
Ursa
* Riki can detect early Roshan attempts because of Cloak and Dagger if he frequently checks the Pit.
* Ursa cannot Enrage when in Smoke Screen (Black King Bar will help though).
* Even if Ursa gets vision over him, Riki can Blink Strike away or use Tricks of the Trade after Ursa's initiation to avoid all Fury Swipes damage until Earthshock's slow is gone.
Additional:
* Riki can detect early Roshan attempts because of 
Cloak and Dagger if he frequently checks the Pit.
* Ursa cannot Enrage when caught in 
Smoke Screen and will miss his attacks (although Black King Bar will help with this issue).
* Even if Ursa gets vision over him and initiates with Earthshock, Riki can 
Blink Strike away or use 
Tricks of the Trade after Ursa's initiation to avoid Fury Swipes' damage until Earthshock's slow is gone.
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.
Ursa
* Slark can detect early Roshan attempts due to 
Shadow Dance if he frequently checks the Pit.
* Enrage cannot restore attributes stolen by 
Essence Shift and will reduce his physical damage output.
* Even if Ursa initiates with Earthshock, Slark can 
Pounce away or use 
Dark Pact after Ursa's initiation to avoid Fury Swipes' damage until Earthshock's slow is gone.
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.
Ursa
* Storm Spirit can steal 
Aegis of the Immortal during Roshan attempts through the Pit, because of his 
Ball Lightning.
* Ursa has no way to catch a slippery Storm Spirit, as Earthshock's slow will do nothing to stop Storm Spirit from using Ball Lightning.
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.
Ursa
* Slardar is one of the few meele heroes who can lane against Ursa in the early game, out harassing him with Bash of the Deep, and running away from a bad engagement with Guardian Sprint
* Corrosize Haze can force Ursa to cast Enrage defensively instead of offensively
* With Corrosize Haze, Slardar's team can quickly dispatch of Roshan, denying one of Ursa's greatest advantages
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.
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.
Ursa
* Due to Tiny's non-existent agility gain, high physical damage heroes are more effective against him (
Clinkz, Templar Assassin, Ursa, Wraith King etc).
Ursa
* Ursa cannot effectively fight against Phantasm's illusions with his single-target damage.
* Chaos Bolt's potentially long stun with Chaos Bolt gives Ursa little opportunity to Enrage.
Additional:
* Ursa has no way to clear illusions quickly, making him vulnerable to 
Chaos bolt and 
Phantasm combo.
* 
Reality Rift can quickly relocate or reinitiate on Ursa once the duration of Enrage is over.
* Phantasm can be used to dispel Earthshock's slow. Manta Style is another item that counter Ursa greatly.
* Ursa has low mobility, once jumped on by Reality Rift, Ursa struggles to escape.
Naga Siren
* Illusion-based and multi-unit heroes can take advantage of Chaos Knight's lack of area damage: Naga Siren, Phantom Lancer, Broodmother
Ursa
* 
Doom makes Ursa less disruptive, and it cannot be dispelled with Enrage upgraded with Aghanim's Scepter.
Ursa
* High health heroes (
Axe, 
Doom) fall fast with Fury Swipes stacks.
Ursa
* Heroes who can provide constant vision inside the Roshan Pit can negate one of the strongest advantages of Ursa, which is the possibility of quickly killing Roshan at the early game, with minimum itemization needed (
Clockwerk, 
Beastmaster, etc).
Naga Siren
* Heroes with long cast animations can be continuously interrupted by Battery Assault: 
Centaur Warrunner, Jakiro, Leshrac, Naga Siren, Underlord.
Ursa
* Ursa's high physical burst damage combined with his big attack speed and durability makes him a very bad target for Power Cogs.
* Even with 
Blade Mail, Ursa's Enrage will negate most of the reflected damage.
Ursa
* Heroes who can delivers a big chunk of damage in few hits will find themselves struggle against Templar Assassin's Refraction: Sven, Phantom Assassin, Ursa, Wraith King, Lifestealer
Additional:
* Templar Assassin usually places 
Psionic Traps inside the Roshan Pit (and can teleport herself to the traps with an Aghanim's Scepter), preventing Ursa from killing Roshan without getting noticed by the enemy team.
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.
Ursa
* Earthshock can slow down Chen and deal damage to both, Chen and his creeps.
* Many stacks from Fury Swipes combined with Overpower can guaranatee a kill for Ursa before Chen can save his allies with 
Hand of God.
* Enrage only makes Chen's attacks and his creeps's attacks tickle Ursa.
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.
Ursa
* Ursa can deal lots of damage during the laning phase before Terrorblade can have 
Sunder available.
* Even if Terrorblade succeeds to use Sunder on Ursa, Enrage's damage reduction can help Ursa survive after Terrorblade has used Sunder him while also making Terrorblade's attacks tickle, even during Metamorphosis for it's duration.
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.
Ursa
* Jumping on Ursa with Life Break is often suicide for Huskar, as he will be immediately bursted down with Fury Swipes.
Additional:
* Huskar likes fights with a long duration and is usually at low health, making him vulnerable against Ursa's physical damage.
* Jumping in with Life Break against Ursa is suicide, as Enrage, Overpower, and Fury Swipes will easily shred 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.
Ursa
* 
Fade Bolt is not enough to burst Ursa, and even more so with Enrage active.
* The damage reduction from Fade Bolt is not effective due to Fury Swipes.
* Enrage lessens the lockdown duration from 
Telekinesis due to its status resistance.
* Ursa can easily melt 
Rubick down with Fury Swipes and Overpower if he gets close enough.
* Few of Ursa's spells grants utility for Rubick, as Rubick cannot steal the Fury Swipes passive.
* Enrage provides Rubick with some sort of survivability, yet Rubick generally wastes the duration in the front line as he does not have a constant damage source.
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.
Ursa
* Early game gankers can make life very difficult for a Sniper if he keeps being caught: Ursa, 
Pudge, 
Earth Spirit.
Naga Siren
* Ensnare with her attacks allows Naga Siren to gank Sniper easily.
* Rip Tide removes Sniper's very little armor.
Ursa
* 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.
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.
Ursa
* Heroes with either magical, physical or pure damage burst: 
Bane, 
Ember Spirit, Leshrac, Lina, Luna, Nyx Assassin, Phantom Assassin, 
Skywrath Mage, 
Tinker, Ursa, Void Spirit.
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
* Sand King and 
Phoenix have many tools to deal with multiple enemies at once, which will work well against a crowd of illusions.
Ursa
* Ursa can easily unleash a number of attacks in an incredibly short amount of time, easily destroying the 
Supernova in a couple of seconds regardless of Fire Spirits' debuff. His Enrage also dampens any damage Phoenix might toss at his direction, as well as remove any debuffs Phoenix may place on him.
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.
Naga Siren
* Heroes who rely on illusions will see them destroyed easily by Overwhelming Odds: Phantom Lancer, Chaos Knight, Terrorblade, Naga Siren
Ursa
* 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
Naga Siren
* Song of the Siren lasts long enough to prevent a successful 
Duel (but only if Naga wasn't the target).
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
* 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.
Ursa
* Earthshock prevents Shadow Fiend from escaping after Ursa used his Blink Dagger to get on top of him.
* Overpower and Fury Swipes allow Ursa to quickly kill Shadow Fiend.
* Enrage keeps Ursa alive in a manfight with Shadow Fiend and allows him to stay close, even if Shadow Fiend uses Requiem of Souls.
Ursa
* If Ursa uses Enrage, Pugna's Life Drain is next to worthless against him, due to Ursa taking 80% less damage, therefor Pugna heals by only 20% of the damage that the spell normally deals.
* It also dispels Decrepify, Even if you wait until he casted it, he can still dispel it with Shard upgraded Earthshock
* Ursa also commonly builds Skull Basher. With his high Attack Speed from Overpower. he can easily cancel Life Drain
* If Decrepify is defensivly casted, Ursa can still cast Earthshock both to slow you, and to deal amplified magic damage. He also commonly builds a 
Nullifier
* If Ursa jumps on you with a Blink Dagger he can easily wipe you out with Overpower.
* Ursa's Overpower can destroy a full health 
Nether Ward and still have a few swipes leftover, Also Ursa's low mana spells means he takes negligible damage from the Nether ward anyway.
* Ursa is also a common Diffusal Blade carrier, using it to both amplify his damage, but as his primary way to catch fleeing heroes
* Pugna is also the primary target of Ursa, due to him being both quite squishy, and a serious threat to his team, Ursa prioritizes the weakest link as Fury Swipes stacking damage will quickly demolish them, allowing Ursa to safely switch heroes
Ursa
* Low armor and lack of escape makes Pudge vulnerable to Ursa, specially when he gets his Blink Dagger.
* If Pudge lands a 
Meat Hook on Ursa, Ursa can simply face Pudge head on provided he can burst him down before any follow up disables.
* Enrage's Aghanim's Scepter upgrade allows Ursa to dispel Pudge's 
Dismember.
Ursa
* Silencer relies on preventing enemies from using abilities in teamfights with Arcane Curse, Last Word, and Global Silence. However, they are ineffective against Ursa since he relies more on items and attacks than abilities.
* Against a carry Silencer, Enrage can help Ursa reduce all damage he takes, even Glaives of Wisdom's pure damage will just tickle Ursa while his Enrage is active.
Ursa
* Fury Swipes will keep stacking on Tidehunter since it cannot be dispelled by Kraken Shell and its bonus damage cannot be reduced by Anchor Smash.
* Enrage dispels the slow from Gush, and if upgraded with Aghanim's Scepter, can even dispel Ravage's stun.
Ursa
* Chemical Rage will rarely save Alchemist against Ursa's Fury Swipes.
* Enrage allows Ursa to both be a threat to Alchemist and avoid his over time damage.
Ursa
* Ursa's massive physical damage can destroy Kunkka quickly.
* Enrage can be activated before being hit by Ghostship to prevent most of the damage.
* Earthshock slows Kunkka's movement speed. With no escape abilities, Kunkka is easy prey.
Ursa
* With Aghanim's Scepter upgraded 
Infest, Lifestealer can use it on enemy heroes to attack them and disarm them from inside, even if they are spell immune, which can give him the edge over the heroes he's weak against like Ursa, Phantom Assassin, Terrorblade or Troll Warlord.
Ursa
* Lifestealer will struggle to duel Ursa in all stages of the game due to Fury Swipes, which pierces magic immunity. Ursa can also stand up to Lifestealer with Enrage, which dramatically reduces incoming damage and further delay Lifestealer's Feast.
Additional:
* Lifestealer's 
Feast will most likely not out-heal the damage from Fury Swipes and Overpower in the early to mid game.
Naga Siren
* Heroes with illusions: Chaos Knight, Naga Siren, Phantom Lancer, Terrorblade
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.
Ursa
* Even though Ursa is a hero who relies on direct attacks to be effective, Fury Swipes does not work on allies if Ursa is affected by Winter's Curse, mitigating a majority of Ursa's damage. In addition, Ursa's unimpressive attack speed and attack damage without Overpower and Fury Swipes means that he deals little to no damage to allies during Winter's Curse.
* Aghanim's Scepter upgraded Enrage allows Ursa to survive Winter Wyvern's initiation with Winter's Curse.
Ursa
* Heroes with weaker mobility will struggle to keep up with Night Stalker: Gyrocopter, Ursa, 
Drow Ranger
Ursa
* Heroes with stronger lane presence that can threaten to kill him: 
Batrider, Juggernaut, Ursa, 
Monkey King, 
Razor.
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.
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.
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
* 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.
Ursa
* Ursa is a special mention because despite Bulwark diminishing most of the damage Ursa does, he is quite durable, especially with Enrage, discouraging the aggressive all-in playstyle of Mars; Ursa can simply not target Mars.
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.
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
* 
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.
Ursa
* Fury Swipes is not protected by Blade Fury and allows Ursa to harass Juggernaut anytime.
* Enrage reduces the damage taken from 
Omnislash.
Naga Siren
* Illusion-based heroes are effective against Omnislash and Juggernaut's single-targeted damage: Naga Siren, Chaos Knight, Terrorblade,Phantom Lancer.
Ursa
* Heroes with burst damage of their own won't be afraid to go toe to toe with Void Spirit, like Ursa, Lifestealer, or Axe.
Ursa
* Ursa can shred Warlock's Golems in a few seconds with Fury Swipes and Overpower.
Ursa
* Low mobility heroes: Heroes with no/little means of traveling fast have difficulty getting to/away from Bounty Hunter due to his slowing Jinada and hastening Track. Few examples of such heroes are: 
Crystal Maiden, 
Sniper, Ursa, Witch Doctor, etc.
Ursa
* Ursa with Enrage
* 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.
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 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
* 
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.
Ursa
* Fury Swipes damage is not reduced by Atrophy Aura, essentially bypassing Underlord's only natural defense.
* Enrage can easily dispel the root of 
Pit of Malice.
* However, Ursa has nothing to intercept Underlord and his team when they are grouped up for the teleportation with Fiend's Gate outside of Earthshock.
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.
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.
Ursa
* Ursa's status resistance from Enrage reduces duration of Medusa's Stone Gaze.
* Ursa can stack damage with Fury Swipes easily against her Mana Shield in a prolonged team match.
Additional:
* Medusa's tankiness doesn't help her very much against Fury Swipes in long teamfights.
* With no escape mechanism and a slow movement speed, getting jumped on by Ursa usually spells a quick end for Medusa in the early game.
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.
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.
Ursa
* Fury swipes can tear Dragon knight down as it stacks infinitely.
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.
Ursa
* Light Strike Array has a long delay, making her vulnerable for Ursa's burst.
* Enrage can protect Ursa against Lina's high magical burst.
Ursa
* Heroes who rely strongly on melee physical damage will fare badly against Omniknight's Guardian Angel: Phantom Assassin, Juggernaut, Dragon Knight, Lycan, Ursa, Troll Warlord
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.
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.
Ursa
* All assassin-type carries in a one against one situation: 
Meepo, Phantom Assassin, Riki, Ursa. Luna's only chances are that she buys Ethereal Blade or Black King Bar to gain a slight edge against them, or both items if necessary.
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
* 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.
Ursa
* Enrage with Aghanim's Scepter can dispel Flaming Lasso.
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.
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
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
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 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
* 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.
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.
Ursa
* Enrage will make it very difficult to burst him down.
* Zeus has little armor, HP and mobility; Ursa's favorite kind of target.
Ursa
* Lycan's ultimate makes him immune to slows from Ursa's Earthshock as well as allowing him to outmaneuver Ursa during Enrage. Lycan can also easily chase down Ursa while shapeshifted, should Ursa try to flee.
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.
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.
Ursa
* Timbersaw's physical survivability revolves around Reactive Armor, which is largely ignored by Fury Swipes due to the extreme amounts of damage it does in a very few number of attacks.
* Timbersaw's burst damage will not do much against Enrage, although he could easily use Timber Chain to escape, wasting the duration of it.
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.
Ursa
* Ursa struggles against heroes with strong (and especially undispellable) disables (
Disruptor, Puck, Shadow Demon, 
Outworld Destroyer and etc).
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
Ursa
* Assuming they have not bought anti-evasion items, attack-dependent heroes such as Ursa, Terrorblade or Lifestealer can be a minor threat for Phantom Assassin early in the game, and may even be completely dominated by her thanks to her evasion.
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.
Ursa
* 
Viper Strike is a strong and breaks Fury Swipes, undispellable slow, making it much easier to kite Ursa for everyone.
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
* 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.
Ursa
* Enigma lacks burst damage, and that makes him vulnerable to heroes who can recover themselves and turn the fight around to their advantage after Enigma finishes his initiation: Faceless Void, Terrorblade, Ursa, Weaver, Broodmother, Slark, Abaddon, Wraith King, Lifestealer.
Naga Siren
* Axe will destroy her illusions by proccing 
Counter Helix more often due to him being hit by more attacks.
Ursa
* Enrage reduces the damage from Blade Mail and Counter Helix to a minimum, forcing Axe to play around Ursa's ultimate ability.
* Overpower and Fury Swipes stacks damage overwhelming for Axe, despite his high health.
Ursa
* Ursa struggles against heroes with strong (and especially undispellable) disables (
Disruptor, 
Puck, 
Shadow Demon, 
Outworld Destroyer and etc).
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.
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