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.
Winter Wyvern
* Timbersaw relies on dealing massive amounts of pure damage, making Cold Embrace a good setup for his nukes.
* If he has Reactive Armor stacks, Timbersaw can tank the damage from his allies if he is targeted by Winter's Curse. If he's not the target, Timbersaw's abysmal attack damage will contribute next to nothing when he is cursed to attack an ally.
* As Timbersaw commonly buys Lotus Orb, he can use it to reflect Winter's Curse back to Winter Wyvern if she uses it impulsively on him or any other hero while affected by it.
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.
Winter Wyvern
* Heavy nukers will do well against Cold Embrace (
Lina, 
Zeus etc).
Additional:
* Any ally that Winter Wyvern tries to save with 
Cold Embrace can still be damaged by all of Zeus's spells.
* If Winter Wyvern tries to juke vision by flying up a cliff or in the trees, Zeus can gain vision there with Lightning Bolt or Thundergod's Wrath.
* If Zeus is forced to attack an ally by 
Winter's Curse, his unimpressive attack damage and attack speed means they won't be hurt much by him. Zeus will also stay near the back of fights away from his allies, making a deadly Curse less likely.
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.
Winter Wyvern
* Cold Embrace is no salvation against 
Lucent Beam and Eclipse.
* Moon Glaives will not hit a hero affected by Winter's Curse, making it weak against allies, but strong versus enemies.
* Luna has better night vision provided by Lunar Blessing than Winter Wyvern when affected by Arctic Burn.
Additional:
* Cold Embrace is no salvation against Lucent Beam and Eclipse.
* Moon Glaives will not hit a hero affected by Winter's Curse, making it weak against allies, but strong versus enemies.
* Luna has better night vision provided by Lunar Blessing than Winter Wyvern when affected by Arctic Burn.
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
* 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.
Winter Wyvern
* Heavy nukers will do well against Cold Embrace (Lina, Zeus etc).
Winter Wyvern
* Cold Embrace makes its target immovable, allowing Ancient Apparition to easily land Ice Blast, or a Cold Feet stun.
* Ice Blast also negates healing from Cold Embrace.
Additional:
* 
Ice Blast disables the healing component of Cold Embrace, making it essentially a 4 second stun on an ally and a perfect setup for Ice Blast.
* If 
Cold Feet is cast on an Allied hero affected by Cold Embrace, it will almost guarantee the Ally comes out stunned.
Winter Wyvern
* Winter Wyvern cannot handle the Zombies created by Undying's Tombstone very well. In most situations, Zombies will have more movement speed than her.
* Undying can gain one or two easy Decay stacks on an ally in Cold Embrace. The ally will still take the damage as well.
Additional:
* Winter Wyvern cannot handle the Zombies created by 
Tombstone very well. In most situations, Zombies will have more movement speed than her.
* Undying can gain one or two easy 
Decay stacks on an ally in Cold Embrace. The ally will still take the damage as well, since it is magical.
Naga Siren
* Mirror Image's illusions increase Echo Slam's damage.
Additional:
* Earthshaker's strong AoE abilities can clear Naga Siren's illusions, or at least make it easier to distinguish the real one by the damage they take.
* 
Echo Slam deals more damage against more enemies, which can be devestating against Naga Siren and her illusions.
Naga Siren
* 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.
Winter Wyvern
* Cold Embrace is the perfect setup for all his nukes - 
Chaos Meteor, 
E.M.P. and especially global 
Sun Strike.
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.
Winter Wyvern
* 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.
Winter Wyvern
* Cold Embrace is a death sentence against Pugna, since its the perfect setup for all his abilities, especially 
Life Drain.
* 
Decrepify can be cast to save the ally under Winter's Curse effect, wasting most of its duration.
* Winter Wyvern's abilities require a lot of mana, allowing 
Nether Ward to deal lots of damage.
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.
Naga Siren
* 
Flak Cannon and 
Call Down can easily clear Naga Siren's illusions.
Winter Wyvern
* Cold Embrace is a perfect setup for Mystic Flare.
* Winter Wyvern is a spellcaster, and the 6 second silence from Ancient Seal can prevent her from contributing much.
* Because Skywrath Mage tends to stay back in fights, Winter Wyvern will have to get close to a teamfight to cast Winter's Curse on him. And if she chooses to cast it on one of his allies, his low attack speed and damage means that he won't do much.
* However, bear in mind that Skywrath Mage has seriously awful armor, and that can make him an adequate target to being turned against his own team with Winter's Curse, which can result in his death quickly.
Additional:
* Cold Embrace is the perfect setup for 
Mystic Flare, and his 6-second silence is good against Winter Wyvern in general.
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.
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.
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.
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 with long cast animations can be continuously interrupted by Battery Assault: 
Centaur Warrunner, Jakiro, 
Leshrac, Naga Siren, Underlord.
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
* 
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).
Naga Siren
* Heroes with long-lasting, undispellable debuffs will pinpoint the true Naga Siren: Spirit Breaker, Bloodseeker, Witch Doctor.
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
* Heroes who are reliant on illusions or summons: Chaos Knight, Broodmother, Naga Siren.
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
* 
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
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.
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.
Winter Wyvern
* Heroes with the ability to heal allies will not be able to heal heroes affected by 
Doom: Chen, 
Dazzle, 
Io, 
Oracle, 
Omniknight, Witch Doctor, 
Winter Wyvern, 
Abaddon, etc.
Winter Wyvern
* All of Tinker's damage is magical and pure, which makes Cold Embrace a good setup for his nukes.
* Winter's Curse is very hard to cast on Tinker because he usually stays in the back-lines in team-fights. In turn, Tinker has mediocre attack damage and will contribute very little when he is cursed to attack an ally. He can also save his ally under Winter's Curse effect with 
Ethereal Blade and 
Defense Matrix.
Naga Siren
* Illusion heroes, such as Naga Siren, Phantom Lancer, Chaos Knight, Terrorblade will become strong against Tinker in the late game. Without Aghanim's Scepter Tinker is forced to defensively disarm heroes with Laser, leaving illusions free to deal physical damage which Tinker's low armor makes highly effective. In addition, 
Mjollnir or Battle Fury, two common pickups against illusion heroes, don't work well on Tinker at all.
Naga Siren
* 
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.
Winter Wyvern
* Winter Wyvern's Winter's Curse turns Morphling's high attack damage and attack speed against his targeted teammate.
Naga Siren
* Medusa's 
Split Shot and 
Mystic Snake combined with Mjollnir, a common item for Medusa, will whittle down all of Naga Siren's illusions, including Naga Siren herself.
* Medusa's 
Stone Gaze can disable Naga Siren even for the duration of Song of the Siren and even if Naga Siren is spell immune, discouraging Naga Siren from even trying to use Song of the Siren to save herself or counter-initiate against Medusa.
Additional:
* Medusa's Split Shot and Mystic Snake combined with Mjollnir, a common item for Medusa, will whittle down all of Naga Siren's illusions, including Naga Siren herself.
* Medusa's Stone Gaze can disable Naga Siren even for the duration of Song of the Siren and even if Naga Siren is spell immune, discouraging Naga Siren from even trying to use Song of the Siren to save herself or counter-initiate against Medusa.
Naga Siren
* Heroes that build 
Diffusal Blade or can fit it well into their item build will also make Medusa much less tanky: 
Riki, Naga Siren, Terrorblade, 
Juggernaut, Spectre, 
Slark.
Naga Siren
* Axe will destroy her illusions by proccing 
Counter Helix more often due to him being hit by more attacks.
Winter Wyvern
* Heroes who can stop Axe from getting close will severely inhibit his presence in fights: 
Bristleback, 
Crystal Maiden, 
Batrider, Arc Warden, Winter Wyvern, 
Clockwerk
Winter Wyvern
* Arctic Burn and Splinter Blast's debuffs are can be dispelled with with 
Dark Pact. Arctic Burn also cannot be used to escape against 
Pounce.
* Even though Cold Embrace can protect it's owner from Slark's direct attacks, Slark can still gain 
Essence Shift stacks from attacking heroes affected by it.
* However, Essence Shift works against allies, and Slark's low health pool means that if he's the target for Winter's Curse, he will go down very quickly as Winter's Curse cannot be dispelled at all.
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
* 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.
Winter Wyvern
* 
Arctic Burn allows Winter Wyvern to escape Lycan, even when he uses his ultimate.
* 
Splinter Blast is very effective in dealing with Lycan's summons.
* Cold Embrace saves allies from Lycan's raw physical damage and can buy allies enough time to turn the tide of battle.
* Winter's Curse stops Lycan in his tracks and is very effective because of his summons.
Additional:
* All of Lycan's damage is physical which is totally negated by Cold Embrace.
* Lycan often moves around with large amount of creeps, wolves created by 
Summon Wolves and neutral creep dominated by 
Helm of the Dominator which can be easily cleared by Splinter Blast or used as a great source of damage by Winter's Curse. If you catch Lycan with creeps nearby and affected by 
Shapeshift using Winter's Curse on him will most certainly end up with his death.
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.
Winter Wyvern
* Cold Embrace can protect allies from Lone Druid and the Spirit bear, who mainly deal physical damage
* Winter's Curse can turn Lone Druid and the Spirit Bear against his teammates.
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.
Winter Wyvern
* Cold Embrace can render the extra attack speed from 
Overcharge meaningless.
* Splinter Blast and Winter's Curse are very affective against Io, as it has to stay close to his Tethered 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.
Winter Wyvern
* Broodmother, Nature's Prophet, Phantom Lancer by their nature offer very good target for Splinter Blast and Winter's Curse.
Naga Siren
* Illusion-based and multi-unit heroes can take advantage of Chaos Knight's lack of area damage: Naga Siren, Phantom Lancer, Broodmother
Winter Wyvern
* Cold Embrace protects targets affected by Reality Rift.
* Winter's Curse turns Phantasm illusions against Chaos Knight or a teammate.
* Splinter Blast deals decent area damage to Phantasm illusions.
* Arctic Burn's percentage-based damage quickly wears down Chaos Knight's high max health.
Additional:
* Winter Wyvern can make Chaos Knight's illusions attack the real one, provided the player knows who it is.
* Alternatively, Winter's Curse can make Chaos Knight and all his illusions attack one of his allies.
* Cold Embrace protects ally who is focused by Chaos Knight.
* Splinter Blast deals decent area damage to Chaos Knight's illusions.
* Chaos Knight's high health pool and tendency to not build magic resistance items will make Arctic Burn deal a lot of damage to him and his illusions.
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.
Winter Wyvern
* Terrorblade and his illusions deal huge damage, which might used against him and his team with Winter's Curse.
Naga Siren
* Heroes who rely on illusions will see them destroyed easily by Overwhelming Odds: Phantom Lancer, Chaos Knight, Terrorblade, Naga Siren
Naga Siren
* Song of the Siren lasts long enough to prevent a successful 
Duel (but only if Naga wasn't the target).
Winter Wyvern
* Cold Embrace saves allies from dying in Duels.
* Winter's Curse turns Legion Commander's high damage against her allies, giving the enemy team little time to react.
* However, Winter Wyvern lanes very poorly against Legion Commander due to Press the Attack removing all the debuffs she can give. Winter Wyvern also has little chances of surviving if she gets Dueled herself.
Additional:
* Cold Embrace is very effective against Duel.
* Also, casting Winter's Curse at 
Legion Commander while an ally is in a Duel will stun her for most of the duration, possibly preventing lethal damage dealt to your ally. It can also turn her high-damage against her teammate.
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.
Winter Wyvern
* Many physical-only single-target heroes like 
Lifestealer, Sven, Wraith King, Phantom Assassin, Templar Assassin can have their damage mitigated by Cold Embrace.
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.
Winter Wyvern
* Any hero that can nullify effects of Chronosphere: (Keeper of the Light with Aghanim's Scepter during daytime, Winter Wyvern), banishing him or Faceless Void (
Outworld Destroyer, Shadow Demon, 
Earth Spirit with Aghanim's Scepter) or protecting him in other ways (Dazzle, Oracle, Abaddon) can greatly limit Chronosphere's potential.
Naga Siren
* Heroes with illusions: Chaos Knight, Naga Siren, Phantom Lancer, Terrorblade
Winter Wyvern
* Many physical-only single-target heroes like Lifestealer, Sven, Wraith King, Phantom Assassin, Templar Assassin can have their damage mitigated by Cold Embrace.
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.
Winter Wyvern
* Many physical-only single-target heroes like Lifestealer, Sven, Wraith King, Phantom Assassin, Templar Assassin can have their damage mitigated by Cold Embrace.
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.
Winter Wyvern
* Cold Embrace mitigates Primal Roar's single-target initiation on allies.
* Winter's Curse can turn Beastmaster's summons and Inner Beast against his teammate.
Additional:
* Beastmaster's summons and 
Inner Beast are very useful to attack his cursed teammate.
* Cold Embrace effectively mitigates 
Primal Roar's single-target initiation on allies.
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.
Winter Wyvern
* Cold Embrace can protect Troll Warlord's target, especially during Battle Trance.
* Winter's Curse can turn Troll Warlord's high physical damage and attack speed against his allies.
Additional:
* Cold Embrace will protect your ally from being damaged if he gets focused by Troll, although be careful as 
Fervor will keep gaining stacks even while Cold Embrace is active.
* Fervor works on allies.
* His high attack speed will help to kill his cursed ally faster.
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.
Naga Siren
* Ensnare with her attacks allows Naga Siren to gank Sniper easily.
* Rip Tide removes Sniper's very little armor.
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.
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
* 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.
Winter Wyvern
* Cold Embrace can heal herself or an ally, as well as protecting them from Clinkz's physical attacks and wasting his mana if Searing Arrows is on autocast.
* Winter's Curse allows Winter Wyvern to turn Clinkz's high damage and high attack speed against his allies, or take advantage of Clinkz's fragility if he can't use Skeleton Walk.
Winter Wyvern
* Arctic Burn makes it nearly impossible for Spectre to juke into the trees.
* Cold Embrace negates all of Spectre's physical damage. Furthermore, Cold Embrace will generally outheal 
Desolate.
* Winter's Curse can taunt illusions, not only wasting the entire duration of 
Haunt but also turning its illusions against Spectre's own team.
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 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.
Winter Wyvern
* Many physical-only single-target heroes like Lifestealer, Sven, Wraith King, Phantom Assassin, Templar Assassin can have their damage mitigated by Cold Embrace.
Naga Siren
* Mirror Image can cause Huskar to Life Break the wrong target.
* Rip Tide reduces Huskar's already low armor.
* Song of the Siren allows teams to recover from Huskar's initiation, as well as the damage over time from Burning Spears.
Naga Siren
* Heroes with 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.
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
Winter Wyvern
* 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
Winter Wyvern
* Broodmother, Nature's Prophet, Phantom Lancer by their nature offer very good target for Splinter Blast and Winter's Curse.
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
* 
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.
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.
Winter Wyvern
* Winter's Curse and Splinter Blast can devastate Underlord's team when they are grouped up for the teleportation with Fiend's Gate.
* Cold Embrace can be used to heal Winter Wyvern's allies, and protect them from the attack damage from Atrophy Aura. Bear in mind, however, that the heroes affected by Cold Embrace are easy targets for Firestorm and 
Pit of Malice.
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
* 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.
Winter Wyvern
* Winter Wyvern's Winter's Curse works very well against the increased attack speed from Bloodlust.
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
* 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
* 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.
Winter Wyvern
* Broodmother, Nature's Prophet, Phantom Lancer by their nature offer very good target for Splinter Blast and Winter's Curse.
Naga Siren
* Naga Siren with Mirror Image
* Heroes that can dodge Glimpse:
* Puck with 
Phase Shift
* Riki with 
Tricks of the Trade
* Phantom Lancer with Doppelganger
* Ember Spirit with Sleight of Fist and 
Activate Fire Remnant
* Chaos Knight with 
Phantasm
* Naga Siren with Mirror Image
* 
Tusk with 
Snowball
* Juggernaut with 
Omnislash
* 
Brewmaster with 
Primal Split
* Lifestealer with Infest
* 
Phoenix with 
Supernova
Naga Siren
* 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.
Winter Wyvern
* Cold Embrace saves any ally Sven initiates on and wastes the duration of God's Strength in team fights.
* Winter's Curse can be devastating to Sven's team, as his massive damage can take out a teammate before there is much time to react.
Naga Siren
* 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.
Winter Wyvern
* Winter's Curse, when directly targeted on Enigma, goes through Black King Bar, stopping Enigma's Black Hole channeling. It also turns his team against him, potentially killing him. Even if Enigma gets Linken's Sphere on top of Black King Bar, Splinter Blast can be used to pop Linken's Sphere, and Winter's Curse will stop Black Hole channeling.
* Splinter Blast can be targeted on an eidolon, killing off other eidolons and damaging nearby heroes as well.
Naga Siren
* Sand King and Phoenix have many tools to deal with multiple enemies at once, which will work well against a crowd of illusions.
Naga Siren
* Song of the Siren does not affect Supernova, which allows her and her team to focus the egg while the enemy team is affected by sleep.
* Phoenix cannot use 
Icarus Dive for escaping when rooted by Ensnare.
* However, Phoenix has many area-of-effect abilities that allow him to clear Naga Siren's illusions from Mirror Image.
Naga Siren
* Naga Siren's Song of the Siren may be useful but Poof will destroy all of her illusions.
Winter Wyvern
* Winter's Curse in late game is pretty much the end for Meepo or any of his nearby allies. Natural counter for Winter's Curse like Linken's Sphere or Lotus Orb is meaningless to her if she can land it on one of Meepo's clones.
Additional:
* Meepo's clones usually gets grouped in teamfight making any of them ideal target for Winter's Curse, forcing Meepo to literally kill himself. Also, unlike other heroes he cannot protect himself with Linken's Sphere.
* While Meepo's clones are grouped up, Splinter Blast will hit almost every clone, slowing Meepo and making him easier to fight.
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.
Naga Siren
* Illusion-based heroes are effective against Omnislash and Juggernaut's single-targeted damage: Naga Siren, Chaos Knight, Terrorblade,Phantom Lancer.
Winter Wyvern
* Heroes with abilities that can save teammates are also effective such as Shadow Demon, Dazzle, Oracle, Bane, 
Pugna, Tusk, Winter Wyvern, Io, Underlord, Treant Protector and Keeper of the Light.
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 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
* 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.
Winter Wyvern
* Winter Wyvern's Arctic Burn can also be a useful tool against Centaur, who generally has very high health. Winter's Curse on Centaur can cause Retaliate to damage allies who are forced to attack him.
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.
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.
Winter Wyvern
* Heroes that depend on disrupting fights with ability combos or big ultimate abilities are vulnerable to the long stun of Fiend's Grip: 
Disruptor, Death Prophet, Enigma, Faceless Void, Invoker, 
Lich, Magnus, Mars, Medusa, Outworld Destroyer, Phoenix, Puck, Queen of Pain, Shadow Fiend, Treant Protector, Underlord, Winter Wyvern, Witch Doctor, Zeus.
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.
Winter Wyvern
* Guardian Angel completely counters Winter's Curse if Omniknight is able to cast it.
Additional:
* 
Guardian Angel completely counters Winter's Curse, allowing his team to survive Winter Wyvern's initiation.
* 
Purification and 
Repel are very useful against Arctic Burn, Splinter Blast and Winter's Curse as well.
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
*
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.
*
*
Winter Wyvern
* Outworld Destroyer's pure damage from Arcane Orb can go through
Cold Embrace. 
Cold Embrace using Astral Imprisonment, and steal mana while doing so.
Winter's Curse is reduced due to Arcane Orb being unable to target allies.
Arcane Orb will continue to deal damage to the defenseless hero.
Arcane Orb does not hit his allies when he is taunted by Winter's Curse, making it weak against allies, but strong versus enemies.
Astral Imprisonment can protect a target inflicted with Winter's Curse.
* Outworld Destroyer can negate the healing from
* Outworld Destroyer's damage during
Additional:
* Winter Wyvern must never put her allies in Cold Embrace against Outworld Destroyer as
*
*