* Phantom Lancer with Diffusal Blade will very quickly burn Medusa's mana, making Mana Shield significantly less effective.
* Doppelganger's 1 second invulnerability can be used to dodge Medusa's petrification from Stone Gaze, as well as Mystic Snake.
* Phantom Lancer's illusions outnumber Medusa's targets from Split Shot, likely shielding his team in the process.

* One of Arc Warden's hardest counters, Arc Warden, who has primarily single target damage, will struggle tremendously against Phantom Lancer:
* Flux is paused if even one illusion remains near Phantom Lancer. It can also be dispelled with Doppelganger.
* Phantom Lancer can also easily dodge an activated Spark Wraith, or use his illusions to trigger it safely.
* Phantom Rush allows Lancer to quickly close gap to get inside of Arc Warden's Magnetic Field.
* Phantom Lancer and his clones are able to quickly drain Arc Warden of his mana with a Diffusal Blade. This means Warden's Tempest Double will also be summoned without mana.
Additional:
* Doppelganger dispels Flux.
* Phantom Rush closes the distance between Phantom Lancer and Arc Warden.
* Juxtapose can overwhelm Arc Warden and nullify his kit which is only effective against isolated enemies.

* Anti-Mage easily destroys Mana Shield with Mana Break, especially once he has Manta Style.
* Anti-Mage effectively avoids Stone Gaze with Blink, and can reinitiate after its duration is over.
Additional:
* Mana Break burns Medusa's mana easily, especially when coupled with a Manta Style.
* Can easily initiate on Medusa with Blink, burning her mana or forcing her to use Stone Gaze.
* Mana Void is effective against Medusa's big mana pool and mana usage, presenting a huge hazard to Medusa's allies around her since her Mana Shield still gives her some protection if she has mana.

* Anti-Mage Blinks directly into Magnetic Field, bypassing its protection.
* Anti-Mage's high mobility allows him to deal with Tempest Double while it is split-pushing.
Additional:
* Arc Warden's high reliance on casting abilities leads him to be dependent on mana, which Anti-Mage can quickly burn with Mana Break.
* Blink mitigates the threat of Flux slow and allows Anti-Mage to close the distance between himself and Arc Warden.
* Anti-Mage's ability to farm quickly allows him keep up with Arc Warden's farm while also de-pushing the lanes Arc Warden shoves in with his Tempest Double.
* Anti-Mage also frequently buys Manta Style, and can use it so dispel Arc Warden's items that can threaten an Anti-Mage like Bloodthorn.
* Counterspell significantly reduces the effectiveness of Arc Warden's magical damage.
* However, do keep in mind that when Arc Warden has a Black King Bar, jumping on him alone may not be the best idea for Invoker as it could put him in a bad position, while Arc Warden summons his doubles and rain damage into him.

* With Smoke Screen, Riki will silence and catch Medusa in a surprise with high miss chance flushing her from positions easily in team fights.
* He can deal a huge amount of damage through Cloak and Dagger, even through Mana Shield.

* Smoke Screen combined with Diffusal Blade leaves Arc Warden effectively useless for a while as he struggles to escape the silence with low mobility.
* With Arc Warden's low mobility, Tricks of the Trade often deal decent damage to him before he moves out of it.

* Webbed areas can be used to hit and run, covering distance hastily weakening her on the way and initiating ganks.
* Even though Medusa can hunt down Spiderlings easily when given enough range, Silken Bola will cause her attacks to miss and get her swarmed in no time.
* Medusa usually does not build a Black King Bar to benefit from Mana Shield fully while Broodmother can fit a Diffusal Blade to burn away all of Medusa's mana.
Additional:
* Spin Web will allow Broodmother to pick her own fights and sometimes slip away to ambush Medusa.
* Though Medusa's Split Shot and Mystic Snake can help Medusa deal with Broodmother's spiderlings, Broodmother will create too much of them for her to handle, allowing her to outnumber Medusa's targets from Split Shot and shield her team in process.

* None of Arc Warden's abilities are very effective against Broodmother and her spiderlings.
* A good Broodmother looks to end the match early while Arc Warden, a very item reliant hero, thrives in longer matches.
* Arc Warden has no innate disables to stop Broodmother from lifestealing with Insatiable Hunger and shredding through his relatively lower armor.

* E.M.P. allows Invoker to burn Medusa's mana to weaken Mana Shield.
* Medusa's lack of mobility makes her easy to kite with Invoker's spells.
Additional:
* E.M.P. is a large mana burn nuke which can hit Medusa's Mana shield with enough damage to lose even more mana.
* Deafening Blast disarms Medusa's ability to deal pseudo-AOE damage during teamfights.
* Cold Snap allows the opposing team to repeatedly stun Medusa in short succession, preventing her from successfully casting her ultimate due to its long cast time.

* Invoker's Forge Spirit can negate Flux.
* Provided he does a right combo with Chaos Meteor, Invoker can easily burst down Arc Warden (plus his clone if he spawns it.)
* An early Orchid Malevolence can shut down Arc Warden pretty hard, especially when Invoker has a good lane against him if he kills him early on.
* Deafening Blast and Ice Wall limit's Arc Wardens mobility and damage, crippling him greatly.

* Medusa cannot chase Slark in any way and has no disable beyond her ultimate, making her unable to stop him getting away and regenerating before coming back to finish her off.
* Essence Shift particularly removes 1 intelligence point per hit, thus lowering Medusa's mana pool's cap and leaving her much more vulnerable in prolonged fights.
Additional:
* Medusa is especially vulnerable to Essence Shift, as both strength and intelligence contribute to her effective HP, while agility contributes to her damage.
* Dark Pact when timed right can be used to dispel Stone Gaze right after it petrifies Slark, allowing him to keep attacking Medusa throughout the duration.

* Flux is dispelled by Dark Pact.
* Pounce allows Slark to avoid Spark Wraiths.
* Tempest Double allows Slark to build up Essence Shift stacks, especially when it is being used for split pushing.

* Other heroes who has armor and slow debuffs won't allow Medusa to disengage from combat: Tidehunter, Bristleback, Slardar.

* Heroes with damage-over-time abilities easily allow Bristleback to turn his back in order to proc Bristleback continuously and to massively reduce to damage dealt to him: Arc Warden, Venomancer, Luna.

Additional:
* Arc Warden has relatively lower armor and mobility, which makes him an easy target to apply Quill Spray and Viscous Nasal Goo stacks.
* Arc Warden also does not like to build a Silver Edge as it takes a long time to build up and may slow down the timings for other important items needed in the game like Gleipnir.
* However, do note that in a game where Arc Warden's team has many jumping capabilities or good passives, like a Tidehunter or Spectre, a Silver Edge becomes incredibly valuable on Arc Warden as not only can he run away from the jumps, he effectively gets 2 breaks, and Bristleback may not be the best pick.

* Because of his weak laning phase, Lone Druid absolutely overpowers him in the early to mid game. Lone Druid also directly counters most of his abilities.
* Flux is nullified when the Spirit Bear is nearby.
* Spark Wraith can get soaked by the bear.
* Lone Druid can easily go inside Magnetic Field and punish Zet.

* Chaos Knight can dispel Flux with Phantasm.
* Chaos Knight can use Reality Rift to pull Arc Warden out of Magnetic Field.
* Once Chaos Knight jumps on Arc Warden with Reality Rift, Arc Warden will struggle to escape due to low mobility and lack of stun.

* With her passive Split Shot, Medusa can be easily interrupted by Spiked Carapace during combat, especially during her precious Stone Gaze.
* Mana Burn quickly destroys Mana Shield, especially if Medusa only increases her mana pool by bolstering intelligence (which has the added bonus of increasing Mana Burn's damage).
* Uncontrollable damage from Mystic Snake and Split Shot can trigger Spiked Carapace.
* Medusa lacks single target damage, making a Burrowed Nyx Assassin hard to kill.
Additional:
* Vendetta burns a significant amount of mana on hit, and the damage from the ability drains Medusa's mana pool even further.
* Due to the passive nature of Mystic Snake and Split Shot, it can possibly proc Nyx's Spiked Carapace if he's within range of Medusa's abilities and isn't invisible.
* Medusa lacks single target damage, making Nyx with Aghanim's Scepter extremely hard to deal with if Medusa is the team's main damage source.

* Arc Warden can't use Magnetic Field to stall the damage of Nether Blast on towers, but he can buy Aghanim's Shard to diminish its damage.
* Arc Warden has no innate disables to stop Life Drain and Decrepify
* The short cooldown of both Life Drain and Decrepify also means Pugna can deal with Arc Warden and Arc Warden's clone simultaneously most of the time
* A good Pugna looks to end the match early while Arc Warden, a very item reliant hero, thrives in longer matches.

* Fiend's Grip provides mana drain, which can heavily damage Mana Shield and prevent Medusa from using Stone Gaze.
* Even if she does use Stone Gaze, Nightmare can buy enough time to protect allies and reset the fight.
Additional:
* Fiend's Grip leaves Medusa defenseless, since not only does it deal damage, it also drains mana.

* Chain Frost can deliver high amounts of damage to Arc and his clone

* Arc Warden cannot take Centaur Warrunner very easily, and his nukes are not strong enough to deal with Centaur Warrunner.
* Centaur Warrunner deals huge AoE damage and applies an AoE disable through Hoof Stomp, affecting the double as well the main Arc Warden.
* Magnetic Field is not very effective against melee heroes. And to make things worse, Magnetic Field also increases Arc Warden and his allies's attack speed, meaning Retaliate will deal more damage.
* Stampede catches Arc Warden easily due to his lack of escape mechanisms. However, Arc Warden can counter this problem with Gleipnir, which is a common item on Arc Warden.

* Medusa's tankiness doesn't help her very much against Fury Swipes in long teamfights.
* With no escape mechanism and a slow movement speed, getting jumped on by Ursa usually spells a quick end for Medusa in the early game.
Additional:
* Ursa's status resistance from Enrage reduces duration of Medusa's Stone Gaze.
* Ursa can stack damage with Fury Swipes easily against her Mana Shield in a prolonged team match.

* Storm Spirit can hunt down Arc Warden with his Ball Lightning and kill him quickly due to his lack of escape abilities.
* None of his abilities are effective against Storm Spirit, as they can be evaded with Ball Lightning.

* Medusa lacks mobility or escape mechanisms. Earth Spike and Hex can neutralize her strong damage potential and allow for Lion's team to focus her down.
* In addition to easily breaking her commonly bought Linken's Sphere with its low cooldown, Mana Drain can quickly drain her Mana Shield, making her far less tanky.
* Mana Drain, along with Hex, destroy illusions instantly, which may be extremely helpfull and efficient against core builders of Manta Style, like Medusa herself.

* With Static Link, Razor can effectively make Medusa useless in teamfights by reducing her main damage output. It can, however, be blocked by a Linken's Sphere.
* Plasma Field allows Razor to get on top of Medusa, slowing her already slow movement speed to a mere crawl.
* Eye of the Storm capitilizes on Medusa's low armor and causes her to be very vulnerable, even through Mana Shield.

* Batrider can harass Arc Warden more easily with Sticky Napalm thanks to it's low cooldown and mana cost and because of Arc Warden's lower durability and mobility.
* Batrider can use Flamebreak to push Arc Warden and Tempest Double out of the Magnetic Field.
* With Firefly combined with Blink Dagger, Batrider can move faster while dealing damage to both Arc Warden and Tempest Double.
* Flaming Lasso allows Batrider to separate Arc Warden from both Magnetic Field and Tempest Double and pull him towards Batrider's team. Aghanim's Scepter upgraded Flaming Lasso also allows Batrider to disable both, real Arc Warden and his Tempest Double and pull them towards Batrider's team. And since Arc Warden is not used to buy Linken's Sphere, this can be a great problem to him.
* Since Arc Warden is not used to buy Black King Bar very ofthen In most of the stages of the game, he will be vulnerable to Batrider's magical damage-over-time output in most of the stages of the game.
* However, Batrider needs to approach Arc Warden carefully as Arc Warden can scout Batrider's location with Spark Wraith. Also, Arc Warden tends to buy Gleipnir which combined with Flux's damage over time can be used to prevent Batrider from even using Blink Dagger.
Additional:
* Batrider can harass Arc Warden more easily with Sticky Napalm thanks to it's low cooldown and mana cost and because of Arc Warden's lower durability and mobility.
* Batrider can use Flamebreak to push Arc Warden and Tempest Double out of the Magnetic Field.
* With Firefly combined with Blink Dagger, Batrider can move faster while dealing damage to both Arc Warden and Tempest Double.
* Flaming Lasso allows Batrider to separate Arc Warden from both Magnetic Field and Tempest Double and pull him towards Batrider's team. Aghanim's Scepter upgraded Flaming Lasso also allows Batrider to disable both, real Arc Warden and his Tempest Double and pull them towards Batrider's team. And since Arc Warden is not used to buy Linken's Sphere, this can be a great problem to him.
* Since Arc Warden is not used to buy Black King Bar very ofthen In most of the stages of the game, he will be vulnerable to Batrider's magical damage-over-time output in most of the stages of the game.
* However, Batrider needs to approach Arc Warden carefully as Arc Warden can scout Batrider's location with Spark Wraith. Also, Arc Warden tends to buy Gleipnir which combined with Flux's damage over time can be used to prevent Batrider from even using Blink Dagger.

* 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.

* 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.

* 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.
Additional:
* 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.

* Melee carries who usually buy an early Black King Bar, and have gap closing abilities can be good against the Arc Warden, such as Slark, Riki, Earthshaker with Aghanim's Scepter, Sven with Aghanim's Scepter etc.

* Hard carries who just want to farm and be left alone will not appreciate Primal Beast, heroes such as Medusa, Drow Ranger...

* Heroes that have doubles or clones such as Arc Warden, Meepo or Lone Druid are vulnerable to Muerta's Gunslinger.

* A well-timed use of The Swarm provides vision over heroes with high mobility: Anti-Mage, Arc Warden, Dark Seer.

* Heroes who take a long time to become strong are in for a rough mid game, such as Outworld Destroyer, Magnus, Medusa, and Anti-Mage.

* 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.

* Heroes with extremely slow movement speed will cripple against Solar Bind: Medusa, Viper

Additional:
* Will-O-Wisp will keep Medusa busy after she got hit by Blinding Light.

* Other heroes who has armor and slow debuffs won't allow Medusa to disengage from combat: Tidehunter, Bristleback, Slardar.

* Burning Spear's damage over time can rapidly burn Medusa's mana and health alike.
* Inner Fire can slow and disarm Medusa and also allow Huskar to follow up with Life Break.

* Silencer burns easily through her effective HP from Mana Shield, by taking away her intelligence.
* Arcane Curse punishes her repeatedly casting Mystic Snake to keep her mana pool high. He can force her to use Manta Style before he has cast Global Silence and Medusa usually does not want to build Black King Bar.

* Bulwark can make each of Medusa's attacks target him instead, reducing Medusa's contribution on team fights.
* Spear of Mars stuns Medusa and also pushes her away from teamfights, taking advantage of Medusa's low mobility.
* Arena Of Blood blocks Medusa's attacks from outside the arena.

* Heroes who rely on summons will see them destroyed easily by Overwhelming Odds: Lycan, Arc Warden, Warlock, Chen

* Rolling Thunder hits Arc Warden, his Tempest Double and any allies through Magnetic Field.
* Rolling Thunder also causes Pangolier to take no damage from existing stacks of Flux as well as clear all Spark Wraiths on the way.

* Luna's Moon Glaives allow her to clear Arc Warden's Tempest Double.
* Luna's short range and fast movement speed allow her to fight Arc Warden inside his Magnetic Field.
Additional:
* Luna's Moon Glaives allow her to clear Arc Warden's Tempest Double.
* Luna's short range and fast movement speed allow her to fight Arc Warden inside his Magnetic Field.

* 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.

* Heroes who depends on illusions and summons: Naga Siren, Arc Warden, Broodmother will struggle against Great Cleave.

* Heroes with good escape mechanisms are a nuisance to deal with in the early phase of the game: Slark, Lifestealer, Morphling

* Heroes with good escape mechanisms are a nuisance to deal with in the early phase of the game: Slark, Lifestealer, Morphling

* Arc Warden's Flux is meaningless against Meepo who loves to group up. Meepo is also a very good gap closer, so Arc Warden's Magnetic Field becomes useless.

Additional:
* Flux is severely impaired against Meepo because of Divided We Stand.
* Meepo's farming speed and early powerspikes allows him to pressure Arc Warden before he is capable of fighting effectively.
* Without Black King Bar, Earthbind and Poof can finish Arc Warden quickly before he has time to do much.

* Arc Warden relies on items and abilities, as well as his Tempest Double, to deal damage to enemies. Doom effectively denies that and makes Arc Warden useless in fights.

* Heroes with summons or illusions can counter Flux, such as Beastmaster , Chen, or Shadow Demon.

* Medusa is a fairly immobile hero that deals damage around her with Split Shot. Sniper should outrange her and should stay out of harm's way from Split Shot.
* More importantly, Sniper should have enough attack range to fire at Medusa during her Stone Gaze without turning to stone, so the ultimate is mostly wasted against him.
Additional:
* Sniper can outrange both Medusa's arrows and Stone Gaze, allowing him to focus her down during a teamfight.

* Heroes with summons or illusions can counter Flux, such as Beastmaster , Chen, or Shadow Demon.

* Axe can take advantage of Medusa's awfully low HP to insta-kill her with Culling Blade, making it extremely difficult for her to farm for items to compensate for the lack of strength during early and mid-game while Axe is continuously harassing around.

* Heroes who rely on fast attack speed will also trigger Counter Helix frequently: Faceless Void, Troll Warlord, Anti-Mage, Juggernaut, Arc Warden, Morphling

Additional:
* Magnetic Field doesn't provide a protection against Berserker's Call and Counter Helix and his high attack speed together with Tempest Double will often trigger Counter Helix.
* The threat of a blink and Berserker's Call may make the real Arc Warden stay further back, thus effectively halving the team's damage output for a while.

* Magnetic Field is useless against melee heroes, so Lycan can attack Arc Warden without missing.
* Flux doesn't affect Lycan that much, because Shapeshift grants immunity to slows and because he is never alone.
* If their Tempest Double has been called, Lycan can still kill Arc Warden before the double expires.

* Chen in the early game is a faster pusher than Arc Warden until Arc Warden buys Maelstrom.

* Other heroes who has armor and slow debuffs won't allow Medusa to disengage from combat: Tidehunter, Bristleback, Slardar.