* Ice Path allows Jakiro to easily cancel Freezing Field.
* Freezing Field makes Crystal Maiden an easy target for all of his abilities without a Black King Bar.
* With the Aghanim's Scepter upgraded Macropyre, Black King Bar becomes nearly useless for Crystal Maiden, as its high pure damage over time, long duration and ability to pierce spell immunity will either force Crystal Maiden to forcefully cancel Freezing Field or even discourage her from using it at all.
Additional:
* Ice Path allows Jakiro to easily cancel Freezing Field.
* Freezing Field makes Crystal Maiden an easy target for all of Jakiro's abilities without a Black King Bar.
* Aghanim's Scepter upgraded Macropyre can deal pure damage-over-time and pierce spell immunity, making Black King Bar nearly useless for Crystal Maiden, as its high damage over time and long duration can discourage Crystal Maiden to use Freezing Field. Remember, however, that Crystal Maiden can partially solve this issue by buying Aghanim's Shard, which will allow her to simply walk out of Macropyre.

* 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.

* Battery Assault, Power Cogs, and Hookshot can interrupt Freezing Field, the latter two being able to go through invisibility should Crystal Maiden use Glimmer Cape.
* Rocket Flare can be used to find Crystal Maiden should she try to hide in the trees to try to safely cast Freezing Field.
* Hookshot allows Clockwerk to easily close in on Crystal Maiden and kill her.

* Heroes with long cast animations can be continuously interrupted by Battery Assault: Centaur Warrunner, Jakiro, Leshrac, Naga Siren, Underlord.

* Heroes with channeled abilities can be interrupted by a long-range Fissure: Crystal Maiden, Witch Doctor, Bane, Pugna, Pudge.

* 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.

* Crystal Maiden will be not able to cast her Freezing Field while being constantly stunned by Enigma's Malefice.
* Enigma's Black Hole can cancel Freezing Field's channeling regardless of her Glimmer Cape and Black King Bar.

* 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.

* Crystal Maiden is extremely fragile and she's an easy target for him. She has no real disables that can lock Ember Spirit down, and all of her skill damage can be negated with Flame Guard. The damage from Searing Chains, Flame Guard, and Sleigh of Fist can easily take her down.

* 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.

* Phantom's Embrace can silence Crystal Maiden and disrupt Freezing Field's channeling. Her slow movement speed and fragile nature will also make her an easy target for Stroke of Fate and Ink Swell.

* Heroes who are reliant on illusions or summons: Chaos Knight, Broodmother, Naga Siren.

* Being a hero with low health and abysmal mobility, Lina can nuke her down easily.
* Since Crystal Maiden's Freezing Field is a channeled ability, Lina can use her Light Strike Array to cancel it easily.

* 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.

* Berserker's Call can interrupt Freezing Field, even through Black King Bar and/or Glimmer Cape.
* Battle Hunger makes Crystal Maiden's already bad movement speed even worse.
* Axe frequently builds Blade Mail, which can quickly kill Crystal Maiden if her ultimate is used while he is under its effect.

* Axe will destroy her illusions by proccing Counter Helix more often due to him being hit by more attacks.

* Lucent Beam allows Luna to easily cancel Freezing Field.
* Without Black King Bar protection, Lucent Beam and Eclipse can make a short work out of Crystal Maiden's abysmal health.
* Skilled Luna will always buy Dust of Appearance, allowing her team to have a vision on Crystal Maiden while invisible and during channeling Freezing Field.
* Even with Black King Bar, Luna can still inflict considerable damage on Crystal Maiden with her attacks, which get empowered with Moon Glaives and Lunar Blessing, also smart and skilled Luna will buy Abyssal Blade to cancel Freezing Field even through Black King Bar in case of emergency. And since Crystal Maiden rarely buys Linken's Sphere, this can be a very big problem for her.
Additional:
* Lucent Beam allows Luna to easily cancel Freezing Field.
* Without Black King Bar protection, Lucent Beam and Eclipse can make a short work out of Crystal Maiden's abysmal health.
* Skilled Luna will always buy Dust of Appearance, allowing her team to have a vision on Crystal Maiden while invisible and during channeling Freezing Field.
* Even with Black King Bar, Luna can still inflict considerable damage on Crystal Maiden with her attacks, which get empowered with Moon Glaives and Lunar Blessing, also smart and skilled Luna will buy Abyssal Blade to cancel Freezing Field even through Black King Bar in case of emergency. Forcing Crystal Maiden to buy Linken's Sphere.

* 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.

* In general, heroes with AoE or long range disables (such as Faceless Void with Chronosphere, Pudge with Meat Hook and Elder Titan with Echo Stomp) hinder Crystal Maiden, preventing her from using Freezing Field to help her team in a fight.

* 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.

* Long range disables are really effective against dangerous area controllers and channeling Heroes, like Enigma, Faceless Void or Crystal Maiden, as it may cancel them or prevent enemies from doing further damage while keeping Lion in a relatively safe distance in the warzone.

* 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).

* Fragile supports who die in a few hits against Sven's high physical damage: Crystal Maiden, Vengeful Spirit, Dark Willow.

* 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.

* Grave Chill will make Crystal Maiden's bad movement speed even worse.
* Soul Assumption charges can easily be stacked up from Freezing Field, allowing Visage to nuke enemies multiple times throughout the fight.
* {U:Familiar}'s Stone Form can also be used to interrupt Freezing Field, even while Crystal Maiden is under the effects of Glimmer Cape. Crystal Maiden must purchase a Black King Bar, which is far more costly.

* Cold feet can be used to ensure that the full channel of Freezing Field doesn't go off.

* Juggernaut and Lifestealer have abilities (Blade Fury and Rage respectively) that prevent Crystal Maiden from using her spells on them in the early game, before Black King Bar and other magical reduction is even an issue.

* 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.

* 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.

* Crystal Maiden is squishy, is heavily spell reliant, has low base Intelligence, and is naturally slow, making her an ideal target for Silencer.
* Crystal Maiden's Freezing Field has a similar cooldown to Global Silence, therefore, Freezing Field can almost always be canceled to ruin aggressive Crystal Maiden initiations.

* Gush can make Crystal Maiden's already weak armor even weaker.
* Kraken Shell can dispel Frostbite, preventing him from getting stuck inside Freezing Field.
* Ravage is very useful for interrupting Freezing Field, even while Crystal Maiden is under the effects of Glimmer Cape. Crystal Maiden must purchase a Black King Bar, which is far more costly.

* 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.

* 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.

* Viscous Nasal Goo can hinder Crystal Maiden's already abysmal mobility, which allows Bristleback (or his teammates) to run her down and kill her.
* Bristleback frequently builds Blade Mail, which can quickly kill Crystal Maiden if her ultimate is used while he is under its effect.
* The passive part of Bristleback will trigger many, many times under the damage from Freezing Field, and as the stacks increase, the damage output from each successive cast (or proc) will eat away at Crystal Maiden's small HP pool.

* Sacred Arrow can be used to interrupt Freezing Field from a safe distance, forcing her to cancel it to dodge or get hit.
* Crystal Maiden has very slow movement speed, making her an easy Sacred Arrow target.
* Crystal Maiden has low health and can easily be killed with an Aghanim's Scepter combo or just when hit with an arrow.
* If Frostbite has already been used, Mirana can Leap away even when slowed by Crystal Nova or Freezing Field.

* Boulder Smash and Geomagnetic Grip allow Earth Spirit to easily disrupt Freezing Field, regardless of where Crystal Maiden is due to their incredible range. Earth Spirit is quite possibly the best hero for stopping long channeling abilities, and Crystal Maiden is vulnerable to him without a Black King Bar.
* All of Earth Spirit's spells allow him to easily close in on Crystal Maiden and kill her. Since she is a low health support, she generally stays behind in teamfights, but Earth Spirit can easily close the distance.
* Crystal Maiden has low movement speed and no other escape mechanism, rendering her extremely vulnerable to Earth Spirit's arsenal of long-range, damaging spells.

* The slow from Torrent makes Crystal Maiden's already bad movement speed even worse.
* Kunkka has many tools to interrupt Freezing Field (most notably Torrent, Ghostship and Torrent Storm from Aghanim's Scepter), as she is an easy target while channeling it.
* It is worth noting that most of Kunkka's abilities do not pierce through spell immunity, so purchasing a Black King Bar might help Crystal Maiden in this regard.

* Even with Black King Bar or Linken's Sphere, Pudge's Meat Hook can still cancel Crystal Maiden's Freezing Field as she is a very easy target while channeling it.
* Pudge's Rot can make Crystal Maiden's already bad movement speed even worse.
* Many stacks of Flesh Heap will make it nearly impossible for Crystal Maiden to kill Pudge.
* Pudge's Dismember can also be used to cancel Crystal Maiden's Freezing Field, and alternatively, Pudge can also use it to save allies from getting killed by Crystal Maiden and heal them when upgraded with Aghanim's Shard.
* Crystal Maiden is prone to ganks in the lane or in the off-lane without proper vision. Pudge can take advantage of Crystal Maiden's lack of mobility, and gank her often.
Additional:
* Meat Hook can cancel Freezing Field, even if Crystal Maiden has Glimmer Cape.
* She is also slow and fragile, making her a good target for ganking.

* 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.

* Flak Cannon and Call Down can easily clear Naga Siren's illusions.

* Snowball allows Tusk to easily cancel Freezing Field from a safe distance without putting himself in any danger.
* Walrus PUNCH! is most certainly a high enough damage nuke to easily kill off Crystal Maiden.
* Ice Shards can prevent the already immobile Crystal Maiden from escaping, making her an easy kill for either Tusk or a teammate.
Additional:
* Crystal Maiden's low health and armor make her an easy target for Walrus PUNCH!
* Tusk's Snowball can protect allies and cancel Freezing Field.
* Snowball and Walrus PUNCH! can interrupt Freezing Field.

* 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.

* 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.

* 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.

* Doom alone can easily pick off Crystal Maiden since she is fairly fragile, even with using only basic attacks, Infernal Blade, and Scorched Earth.
* Doom prevents her from using any abilities in a fight, making her impact negligible.
* Devour allows Doom to acquire a stun, allowing him to cancel Freezing Field without having to use Doom.

* 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.

* Naga Siren's Song of the Siren may be useful but Poof will destroy all of her illusions.

* Heroes with little health or magic resistance are easily picked off with Oracle's magic burst, such as Skywrath Mage, Crystal Maiden, or Enchantress.

* Heroes with strong channeling spells like Crystal Maiden's Freezing Field, Bane's Fiend's Grip, and Enigma's Black Hole can easily be interrupted from a long range by Nether Swap, assuming they don't have a Linken's Sphere.

* 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.

* Heroes with long-lasting, undispellable debuffs will pinpoint the true Naga Siren: Spirit Breaker, Bloodseeker, Witch Doctor.

* Duel is a great initiation to target Crystal Maiden with, as it prevents her from using Freezing Field or any other abilities and allowing the enemy team to quickly kill her before she can aid her team in a fight.

* Heroes who rely on illusions will see them destroyed easily by Overwhelming Odds: Phantom Lancer, Chaos Knight, Terrorblade, Naga Siren

* Generally, any fragile heroes will have a hard time dealing with Undying's tankiness, and even more so if Decay is used on them. Some examples are Crystal Maiden and Witch Doctor.

* Heroes with low health are especially vulnerable to Marksmanship's high damage output: Clinkz, Crystal Maiden.

* 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.

* Channeling heroes will not go well against Warlock, especially those who build Black King Bar as Warlock's ultimate ability stun goes through spell immunity. E.g.: Crystal Maiden, Witch Doctor, Enigma, etc.

* In the same vein, heroes with silences — especially with the AoE ones like Death Prophet's Silence — can also prevent Crystal Maiden from being able to impact a fight.

* Heroes with long-lasting, undispellable debuffs will pinpoint the true Naga Siren: Spirit Breaker, Bloodseeker, Witch Doctor.

* 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.

* 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.

* 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.

* Crystal Maiden has a very bad movement speed, so Impale is easy to land against her. Furthermore, even while trapped by Frostbite, Nyx Assassin can still cast Impale.
* Crystal Maiden has very low armor, so Vendetta is very effective.
* Nyx Assassin has two ways to stop Freezing Field, provided she doesn't get a Black King Bar. He can either pop Spiked Carapace and simply walk into the field, or he can use Impale to interrupt the field, since Crystal Maiden has to channel it.
Additional:
* Spiked Carapace easily interrupts Freezing Field.
* Frostbite's damage over time sets up an easy Spiked Carapace stun.
* Crystal Maiden is extremely fragile and dies quickly to Nyx Assassin's burst damage.

* 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.

* Puck has both Waning Rift and Dream Coil to stop Freezing Field's channel regardless of whether or not Crystal Maiden has a Glimmer Cape, as both spells fully affect invisible units.

* 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.

* As Crystal Maiden is squishy with very bad movement speed, Spectre can easily stay on Crystal Maiden with Haunt and Spectral Dagger.
* Late game, with enough farm, Spectre can withstand an entire Freezing Field, possibly even causing Crystal Maiden to kill herself from Dispersion.

* Heroes with slow movement speeds and small health pools (supports like Crystal Maiden or Witch Doctor) are easy targets for Phoenix. Should they be inflicted by its DOT debuffs, they will be very quickly killed without even getting a chance to fight back.

* Sand King and Phoenix have many tools to deal with multiple enemies at once, which will work well against a crowd of illusions.

* Fragile supports with low armor are always a good prey, also her Psionic Trap will wear down most attempts to flee with their built-in disables: Silencer, Crystal Maiden, Warlock, Ancient Apparition, Grimstroke, Witch Doctor

* 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.

* Crystal Maiden's low health pool and slow movement speed make her a tempting and easy target.
* However, it may be wise to build Black King Bar first before attempting to fight her alone, as she can disable you and retaliate with Freezing Field.

* 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.

* Innately fragile heroes will die almost instantly to Reality Rift while Chaos Knight has illusions active: Drow Ranger, Bane, Necrophos, Crystal Maiden.

* Heroes with long-lasting, undispellable debuffs will pinpoint the true Naga Siren: Spirit Breaker, Bloodseeker, Witch Doctor.

* 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.

Additional:
* Shuriken Toss's stun is useful for cancelling Freezing Field from a distance.
* Track can be used for revealing Crystal Maiden when she uses Glimmer Cape.
* Jinada does burst physical damage (which is even bigger if dealt under Track's crits), which is effective due to Crystal Maiden's low HP and armor.
* Bounty Hunter likes to stay hidden from the fight and is less likely to get caught by Crystal Maiden's spells.

* Heroes who can easily harass Crystal Maiden out of lane in the early game (Clinkz, Viper) can prevent Crystal Maiden from being able to level effectively, and can ultimately slow down her level 6, 12, and 18 to a point where enemy carries already have items to address her ultimate.

* Heroes with channeled abilities which Assassinate may cancel at long range: Witch Doctor, Crystal Maiden, Shadow Shaman, Pugna

* Heroes with a low attack speed or are fragile will find themselves unable to deal with Troll Warlord's high physical damage and attack speed, like Crystal Maiden or Sven.

* Heroes with low mobility that rely on spells: Zeus, Lina, Crystal Maiden.

* Lone Druid's early game is good against slow, squishy supports since his bear is very strong early game and an Entangling Claws proc almost always guarantees a kill: Ancient Apparition, Crystal Maiden, Shadow Shaman, etc.

* Vulnerable spellcasters with no escape mechanisms are easy targets for Huskar: Lich, Crystal Maiden, Silencer, Keeper of the Light, Venomancer, etc.

* 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.

* Smoke Screen effectively disables Crystal Maiden's channeling spell: Freezing Field.
* Due to her low health and armor throughout the game, Riki can kill her easily.

* Heroes who rely on channeling abilities can be interrupted in teamfights by Rolling Thunder: Crystal Maiden, Pugna, Witch Doctor

* 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

* 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.

* Heroes with a low health pool (Crystal Maiden, Skywrath Mage etc)

* Crystal Nova helps on farming while applies an area slow.
* Frostbite extends Rubick's lockdown duration while providing extra damage, also serves as a farming ability.
* Freezing Field deals much greater damage thanks to Arcane Supremacy in teamfights.
* Freezing Field is a channeling ability and therefore can be stolen easily.
* Crystal Maiden has no innate ability to interrupt Freezing Field, though it may not be the case for her teammates; Yet a well-times Telekinesis lift or drop can interrupt Freezing Field.
* Consider build items that strengthens Freezing Field, such as Aghanim's Shard, Black King Bar and Aghanim's Scepter to reach its full potential.

* In general, heroes with AoE or long range disables (such as Faceless Void with Chronosphere, Pudge with Meat Hook and Elder Titan with Echo Stomp) hinder Crystal Maiden, preventing her from using Freezing Field to help her team in a fight.

* Heroes that have small health pools and little to no escape mechanisms are even easier prey for Necrophos. Ghost Shroud's slow will allow him to catch him with them, and get nuked down with his abilities, even preventing retaliation due to Reaper's Scythe's stun. Such heroes include Crystal Maiden, Witch Doctor, Warlock or Shadow Fiend.

* 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

* Heroes with large health pools (Pudge) or good innate magic resistance (Anti-Mage) can be very problematic for Crystal Maiden, since even if they are under the effect of her ultimate for the entire duration, the damage output is simply not enough to kill or force them to retreat.

* Crystal Maiden's already low armor and easily interruptible ultimate, Freezing Field can make Slardar her worst nightmare. Crystal Maiden also often builds Glimmer Cape which is revealed by Corrosive Haze.

* Heroes who can easily harass Crystal Maiden out of lane in the early game (Clinkz, Viper) can prevent Crystal Maiden from being able to level effectively, and can ultimately slow down her level 6, 12, and 18 to a point where enemy carries already have items to address her ultimate.

* 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.

* Any hero with a low HP pool is easy for Tinker to nuke down: Crystal Maiden, Enchantress, Gyrocopter, Lion, Riki, Techies, Terrorblade, Necrophos, Invoker.

* Juggernaut and Lifestealer have abilities (Blade Fury and Rage respectively) that prevent Crystal Maiden from using her spells on them in the early game, before Black King Bar and other magical reduction is even an issue.

Additional:
* Crystal Maiden is an ideal target for Lifestealer due to her poor mobility and low health pool. Lifestealer can usually catch up to her simply by casting Rage, as none of her abilities pierce through magic immunity. Freezing Field can potentially make her even more vulnerable to Lifestealer while under Rage as she is even more immobile while channeling it.
* Lifestealer commonly buys Abyssal Blade, which allows him to cancel Freezing Field, even if Crystal Maiden is spell immune.
* Alternatively, Aghanim's Scepter upgraded Infest combined with Abyssal Blade and with items that provide attack speed which Lifestealer commonly buys allow him to to cancel Freezing Field from within the Crystal Maiden.