* Heroes with illusions: Chaos Knight, Naga Siren, Phantom Lancer

* Primal Roar pierces Rage and can disable Lifestealer in fights.

* Naga Siren can easily disjoint, and dispel Corrosive Skin with Mirror Image.
* Since Viper is a single-target hero, he will not stand a chance against Naga Siren because she is an illusion based hero.

* Illusion or summon-based heroes can be a problem to Viper due to his lack of AoE damage: Naga Siren, Phantom Lancer, Beastmaster

* Call of the Wild Hawk can scout Techies as they are placing mines.
* Call of the Wild Boar can clear Proximity Mines.
* The stun of Primal Roar will usually be enough to deal with the squishy Techies before they can try to suicide with Blast Off!.

* Heroes with summons like Broodmother,Enigma, Invoker, Nature's Prophet, Lycan, Visage;or illusions, like Naga Siren, Phantom Lancer, Terrorblade are effective at keeping the choke points and rune spawns safe from Proximity mines in the early game.

* Beastmaster's Hawk can find Tinker easily while he is pushing or blinking into trees.

* Illusion heroes, such as Naga Siren, Phantom Lancer, Chaos Knight, Terrorblade will become strong against Tinker in the late game when Tinker's only area of effect damage, March of the Machines, ceases to kill illusions quickly. 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.

* Multiple attackers thanks to illusions: Phantom Lancer, Chaos Knight, Naga Siren (bonus for her Ensnare). Also despite the visual effects, Templar Assassin does not spill damage against illusions or buildings, so she is not a really good hero to clean up illusions.
* Heroes that can quickly deal damage to her, regardless of how weak they are, can easily break through her Refraction:
* Multiple attackers thanks to summoned units or clones: Meepo, Witch Doctor, Lycan, Enigma, Shadow Shaman
* Multiple attackers thanks to illusions: Phantom Lancer, Chaos Knight, Naga Siren (bonus for her Ensnare). Also despite the visual effects, Templar Assassin does not spill damage against illusions or buildings, so she is not a really good hero to clean up illusions.
* Weak damage but high tick rate or persist in a long time: Slark, Gyrocopter, Queen of Pain, Shadow Shaman (Shackles), Pugna

Additional:
* Ensnare disables Lanaya's invisibility and Blink Dagger (a core item on Templar Assassin), and her illusions will break Refraction easily.

* Attacks from Boars and the attack speed boost from Inner Beast will quickly wear down Refraction.
* True Sight provided by Level 3 Necronomicon can see Templar Assassin in Meld.

* Necronomicon Warrior's Mana Break can deplete Wraith King's mana and prevent him from using Reincarnation.
* Wraith King's lack of area of effect spells makes him easily overwhelmed by Beastmaster's summons.

* 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.

* Heroes with illusions and summons can manfight Night Stalker: Terrorblade, Beastmaster, Broodmother.

* 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 and Crippling Fear.
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.

* Lycan is a carrier built entirely with physical attacks, having 0 AoE presence and no spell power. Due to this, he can't deal with illusions or Naga Siren's Ensnare.

* Primal Roar allows Beastmaster to keep Lycan in place after he used his Shapeshift.

* Naga Siren is a natural split-pusher. With a Radiance equipped, she will easily out-push Nature's Prophet, farming his treants in the process.
* Ensnare prevents Teleportation. Even if he hid inside Sprout, Song of the Siren lasts long enough to prevent him from escaping.
Additional:
* 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.

* 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 will prevent Rubick from spamming his abilities from Spell Steal.
* Mirror Image allows to dodge the incoming stun from Telekinesis (when she is not a target) and it can also to dodge and dispel Fade Bolt's damage reduction debuff.

* Ensnare with her attacks allows Naga Siren to gank Sniper easily.
* Rip Tide removes Sniper's very little armor.

* 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 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.

* Song of the Siren can be used to time out Guardian Angel, giving Naga Siren's team an easy opportunity to counter-initiate.
Additional:
* Song of the Siren will waste Guardian Angel.
* Ensnare fully works on Heavenly Graced targets. However, Ensnare is dispellable with any dispel, and so can be dispelled by Heavenly Grace.
* As an agility hero that relies on illusions, Naga is one of the most natural Diffusal Blade carriers, the bane of every hero with a small mana pool.

* Primal Roar and the slow from Boars makes kiting Ursa very easy.

* 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.

* Primal Roar and the slow from Boars make kiting Troll Warlord very easy.

* Ensnare is good vs bear.
* In teamfights, song of the siren may be used to properly set up and coordinate an attack on Lone Druid in the backline, bursting him down, allowing to completely ignore the bear.
* Druid lack innate AoE capabilities giving him no good way of dealing with illusions.

* Song of the Siren stops him from acting and her illusions can push better than him because Mirror Image has a longer duration.
* Arc Warden does not often build Radiance, which is useful for illusions and countering illusion pushes.
* Mirror Image dispels Flux or prevents Flux's slow.
Additional:
* Her illusions can push better than Arc Warden's Tempest Double because Mirror Image has a longer duration.
* Mirror Image dispels Flux, and the illusions stop Flux from working.

* The Hawk can easily find Monkey King while he is sitting on a tree.
* Wild Axes can knock out Monkey King from tree.
* Boars drastically reduce Monkey King's attack speed, making it harder for him to gain Jingu Mastery stacks.
Additional:
* Wild Axes can chop down trees, making it difficult for Monkey King to utilize Tree Dance well.
* Call of the Wild Hawk can scout Monkey King when he is perched on top of trees.

* Heroes who relies on illusions and summons (Beastmaster, Chaos Knight, etc.).

* Heroes who rely on high mobility are especially vulnerable to Primal Roar: Storm Spirit, Ember Spirit, Queen of Pain.

* 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.

* 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.

* Heroes that create illusions (such as 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 and the aforementioned 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).

* 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

* Skywrath mage also has a terrible time fighting against anything that isn't a hero. As Mystic Flare only affects heroes, his skills are mostly target-based and he has terrible strength and agility, he can easily be kited or harassed by illusion-based heroes like Chaos Knight and Phantom Lancer, or by Heroes that summon other units like Lone Druid, Lycan and Beastmaster.

* Heroes who rely on high mobility are especially vulnerable to Primal Roar: Storm Spirit, Ember Spirit, Queen of Pain.

* Any hero reliant of mobility, like Storm Spirit.

* 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 dealer, so he will not fare well against Naga Siren. He might as well try to Track her, but her Mirror Image will dispel the effect. Also, Ensnare reveals invisible units while they're rooted, putting Bounty Hunter in a tricky situation.

* Illusion-based heroes are effective against Omnislash and Juggernaut's single-targeted damage: Naga Siren, Chaos Knight, Terrorblade,Phantom Lancer.

* Primal Roar takes Sven out of the fight completely, even with Black King Bar.

* Song of the Siren lasts long enough to prevent a successful Duel (but only if Naga wasn't the target).

* Inner Beast helps Beastmaster's team destroy Supernova quickly.

* Primal Roar and the slow from Boars make kiting Tiny very easy.

* 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,Drow Ranger.

* Heroes with disables that ignore spell immunity will render Phantom Assassin quite useless in teamfights throughout the game: Enigma, Vengeful Spirit, Doom, Bane, Beastmaster, Pudge.

* Heroes who rely on high mobility are especially vulnerable to Primal Roar: Storm Spirit, Ember Spirit, Queen of Pain.

* Because only one clone needs to be killed in order to kill Meepo, heroes that excel at singling out enemies can also be a detriment to him, such as Batrider, Beastmaster, Pudge and Clockwerk.

* Illusion and heroes with summons are difficult to kill with Chen's single-target offensive spells: Terrorblade, Phantom Lancer, Chaos Knight, Broodmother, Naga Siren, Lycan, Visage. However, Chen can convert enemy summons with Holy Persuasion, as long as they don't bunch up.

Additional:
* Naga Siren can make landing Chen's combo very hard due to her being an illusion hero.
* Ensnare will prevent Chen from activating Hand of God.

* 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.
Additional:
* Mirror Image can dispel Frostbite.
* Ensnare and Song of the Siren can stop Freezing Field.
* Song of the Siren can allow her team to quickly close the gap on Crystal Maiden.

* Heroes with powerful rooting abilities will disable most of Pangolier's skill, a bonus point if it pierce 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

* Heroes with other kind of disables that pierce spell immunity can hold Pangolier in place during Rolling Thunder: Axe, Beastmaster, Enigma, Magnus, Pudge, Batrider, Bane, Winter Wyvern

* Heroes with disables that go through spell immunity can end Bloodseeker before he has the chance to do anything: Batrider, Beastmaster

* Song of the Siren can be used to nullify the effects of Winter's Curse, and when upgraded with Aghanim's Scepter it also outmatches the heal of Cold Embrace.
* If Winter Wyvern is reckless enough to put an ally in Cold Embrace, Naga Siren will be able to use her Ensnare to extend the disable on the hero affected by Cold Embrace.

* Illusion-based and multi-unit heroes can take advantage of Chaos Knight's lack of area damage: Naga Siren, Phantom Lancer, Meepo, Broodmother

* 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 tankiness. Plus, the said item makes Naga Siren harder to be distinguished from her illusions.