Vengeful Spirit
* Past the mid game, an isolated Vengeful Spirit makes for an easy kill for Anti-Mage.
* Magic Missile is the only disable Vengeful Spirit has against Anti-Mage, but he can either 
Blink away to disjoint the stun or reflect it back against Vengeful Spirit with 
Counterspell.
* Nether Swap isn't very effective against Anti-Mage - if used offensively, Anti-Mage can simply blink away to safety, and if used defensively, Blink's low cooldown allows him to persistently chase as well.
Medusa
* 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.
Vengeful Spirit
* Vengeful Spirit has no strong AoE nuke or disable against Phantom Lancer's Illusions.
* Phantom Lancer is a natural 
Diffusal Blade carrier, which reduces Vengeful Spirit's low mana pool very quickly, leaving her defenseless.
* 
Doppelganger can dodge Vengeful Spirit's abilites.
* 
Phantom Rush with his illusions can chase Vengeful Spirit efficiently.
Medusa
* 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.
Vengeful Spirit
* Vengeful Spirit should carefully consider whether to use her Nether Swap on Tidehunter, as it can easily position him for a 
Ravage on Vengeful Spirit and her allies.
* Due to Magic Missile's high damage, 
Kraken Shell will often proc and clear Tidehunter's debuffs.
Medusa
* Other heroes who has armor and slow debuffs won't allow Medusa to disengage from combat: 
Tidehunter, 
Bristleback, 
Slardar.
Vengeful Spirit
* Frail heroes who lacks mobility: 
Crystal Maiden, 
Enigma, 
Dark Willow, 
Vengeful Spirit.
Medusa
* 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.
Vengeful Spirit
* Heroes who have a high mobility (
Queen of Pain, 
Storm Spirit, 
Slark, etc.).
Medusa
* 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.
Additional:
* 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.
Medusa
* 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.
Medusa
* Ursa's status resistance from 
Enrage reduces duration of Medusa's Stone Gaze.
* Ursa can stack damage with 
Fury Swipes easily against her Mana Shield in a prolonged team match.
Additional:
* Medusa's tankiness doesn't help her very much against Fury Swipes in long teamfights.
* With no escape mechanism and a slow movement speed, getting jumped on by Ursa usually spells a quick end for Medusa in the early game.
Medusa
* 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.
Medusa
* He can use either his own or his double's 
Flux to bypass the spellblock from Linken's Sphere, using the leftover Flux + 
Spark Wraith to slow Medusa's already low move speed to a crawl.
* Arc Warden has a farming advantage with double 
Hand of Midas, and can generally bully Medusa with other items that benefit from duplication.
Vengeful Spirit
* Skywrath Mage should have the upper hand against Vengeful Spirit with Ancient Seal.
* Vengeful is highly dependant on her abilities and has no natural means to deal against silences.
* Her low attack range allows Skywrath Mage to easily bully her out of the lane.
Medusa
* 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.
Medusa
* 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.
* 
Mana Drain is a perfect ability to weaken Medusa's durability as it can quickly drain her Mana Shield, making her far less tanky. Mana Drain can also be used to restore mana of Lion's allies, which can nullify the mana steal from Mystic Snake.
* Mana Drain, along with Hex, destroy illusions instantly, which may be extremely helpfull and efficient against core builders of Manta Style, like Medusa herself.
Vengeful Spirit
* 
Nethertoxin disables Vengeance Aura.
* Vengeful Spirit has no mobility spells aside from Nether Swap, which Viper can take advantage of with his slows.
* Viper can easily bully Vengeful Spirit out of a lane with 
Poison Attack.
Additional:
* 
Viper Strike can disable the attack damage bonus from 
Vengeance Aura and the components of 
Nether Swap.
* Both 
Magic Missile and 
Wave of Terror are counteracted by 
Corrosive Skin, making Vengeful Spirit's fighting harder against Viper.
Vengeful Spirit
* Magic Missile is a solid damage source and lockdown that fits nicely with Rubick's kit.
* Rubick also acquires the secondary Magic Missile with 
Aghanim's Shard.
* Wave of Terror can be used to scout an area to prevent juking or initiate with 
Telekinesis, as well as reducing the armor of enemy team during a teamfight.
* Nether Swap does what it does - saving an ally from danger, initiating on an enemy, or helping with caughting a fleeing hero.
* With Aghanim's Shard, Rubick can lift himself up and drop quickly to a place of safety after the swap. Note that Rubick can only choose to either disable the enemy or save himself at one time with Telekinesis.
Additional:
* All of Vengeful Spirit abilities are very good for Rubick to 
Spell Steal:
* Magic Missile provides an additional nuke/disable to pair with 
Fade Bolt and Telekinesis, respectively.
* Wave of Terror serves as a good scouting/armor reduction skill that Rubick and his team can benefit from.
* Nether Swap complements Rubick's mobility and pairs well with other mobility items he usually builds. He can also use it to save an ally from danger.
Vengeful Spirit
* 
Ball Lightning disjoints an incoming Magic Missile, avoids Wave Of Terror, and allows Storm Spirit to easily escape if he ever gets Nether Swapped.
Medusa
* 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.
Medusa
* 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.
Medusa
* 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.
Medusa
* 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.
Vengeful Spirit
* Heroes who have a high mobility (Queen of Pain, Storm Spirit, Slark, etc.).
Vengeful Spirit
* Heroes who relies on illusions and summons (
Beastmaster, 
Chaos Knight, etc.).
Medusa
* Other heroes who has armor and slow debuffs won't allow Medusa to disengage from combat: Tidehunter, Bristleback, Slardar.
Medusa
* 
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.
Vengeful Spirit
* Heroes with abilities that reduce armor will make Huskar very vulnerable: 
Weaver, 
Dazzle, Bristleback, Vengeful Spirit.
Additional:
* Huskar struggles against heroes that output high physical damage due to his low armor. Vengeful Spirit's Wave of Terror and Vengeance Aura help increase the physical damage of her team.
Medusa
* 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.
Vengeful Spirit
* 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.
Medusa
* 
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.
Medusa
* Medusa's Stone Gaze forces Mars to choose between getting petrified, or turning his vulnerable back on Medusa.
Medusa
* Sniper can outrange both Medusa's arrows and Stone Gaze, allowing him to focus her down during a teamfight.
Additional:
* 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.
Vengeful Spirit
* Heroes with catch to disrupt Sniper's positioning and deliver him into the enemies: 
Batrider, 
Disruptor, 
Pudge, Vengeful Spirit.
Vengeful Spirit
* Magic Missile can stun Chen and deal heavy damage to him.
* Wave of Terror weakens durability of Chen and his creeps.
* Nether Swap can be used to separate Chen away from his creeps, often to certain death from Vengeful Spirit's allies.
Medusa
* Medusa's Split Shot can easily kill Chen's creeps.
* Mystic Snake can quickly kill Chen's creeps and deal intense damage for every killed creep while also draining their mana with each bounce. 
Aghanim's Scepter upgraded Mystic Snake can also disable both, Chen and his creeps upon impact.
* Mana Shield will make it impossible for Chen to burst down Medusa.
* Stone Gaze can disable Chen from using 
Hand of God to save himself or his allies.
Vengeful Spirit
* Vengeful Spirit can interrupt Black Hole's channeling through Black King Bar by using Nether Swap from a safe distance.
* Vengeful Spirit's Level 25 Talent can make her Magic Missile pierce spell immunity, giving her another option to use in conjunction with Nether Swap to cancel Enigma's Black Hole channeling even through both, Black King Bar and Linken's Sphere.
Medusa
* Medusa's Split Shot can make quick work of Enigma's Eidolons and take advantage of their considerable bounty.
* Medusa can also kill Eidolons with her Mystic Snake that can also greatly damage Enigma and drain some of his mana.
* If Medusa activates Stone Gaze at the start of a fight, it can make initiating and landing an effective Black Hole exceedingly difficult, because Stone Gaze can cancel Enigma's Black Hole even through spell immunity, which can discourage Enigma from even trying to initiate with Black Hole.
Additional:
* Medusa's Split Shot can make quick work of Enigma's Eidolons and take advantage of their considerable bounty.
* If Medusa activates Stone Gaze at the start of a fight, it can make initiating — and landing an effective Black Hole exceedingly difficult. Stone Gaze can cancel Enigma's Black Hole even through spell immunity, which can discourage Enigma from initiating with Black Hole.
Vengeful Spirit
* With Nether Swap, Vengeful Spirit can isolate one of the Meepos, making him an easier kill for the team.
* Her Magic Missile gives her an easy way to cancel Meepo's 
Poof, preventing isolated Meepos from fleeing.
Medusa
* Poof won't damage Medusa and she can use Stone Gaze to disable all of Meepo's clones.
* Mystic Snake will easily become the bane of Meepo early game.
Vengeful Spirit
* Certain heroes can mess up with Pangolier's positioning and timing (especially if he intends to use Rolling Thunder during combat): Vengeful Spirit, 
Keeper of the Light, 
Huskar, 
Dark Seer
Medusa
* Split Shot will keep attacking Pangolier even when he is rolling around.
* Stone Gaze stuns Pangolier during Rolling Thunder, or forces him to roll away.
Vengeful Spirit
* With the exception of Magic Missile (unless the player takes the Level 25 Talent "Magic Missile Pierces Spell Immunity"), all of Vengeful Spirit's spells ignore Spell Immunity. This also makes her good against heroes with built-in Spell Immunity like 
Lifestealer or Juggernaut or heroes that tend to pick up Black King Bar, like 
Sven.
Medusa
* Lifestealer's low mobility makes him easy to kite.
* Stone Gaze pierces 
Rage, wasting its cooldown and making Lifestealer unable to fight.
Vengeful Spirit
* Heroes with disables that ignore spell immunity will render Phantom Assassin completely useless in teamfights throughout the game: 
Axe, Enigma, Vengeful Spirit, 
Doom, Bane, Beastmaster, Pudge, Medusa, 
Warlock.
Medusa
* Heroes with disables that ignore spell immunity will render Phantom Assassin completely useless in teamfights throughout the game: Axe, Enigma, Vengeful Spirit, Doom, Bane, Beastmaster, Pudge, Medusa, Warlock.
Vengeful Spirit
* Heroes with high physical and magical damage alike are a huge hazard for Muerta, as they can deal serious damage to her even if she has 
Pierce the Veil active: 
Luna, 
Lina, 
Tusk, 
Broodmother, 
Shadow Fiend, 
Ember Spirit, 
Gyrocopter, Vengeful Spirit, 
Arc Warden, Medusa, 
Shadow Shaman.
Medusa
* 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.
Medusa
* Doom does not disable Mana Shield. As such, Doom's damage is largely mitigated by her mana shield. Additionally, Medusa is not reliant on her abilities to be effective during a teamfight, making Medusa an unproductive hero to target.
* Medusa is an ideal Linken's Sphere carrier. Should one be purchased, and without any additional disables, Doom may find that few opportunities exist to effectively lockdown, disable, and kill Medusa.
Vengeful Spirit
* Wave of Terror grants flying vision over trees, and its wide effect can hit Monkey King and end Mischief.
* Nether Swap can easily cancel Wukong's Command by swapping him out of the circle.
Additional:
* She can easily cancel 
Wukong's Command with Nether Swap.
* Wave of Terror can also detect him while he's on the trees.
Vengeful Spirit
* Nether Swap breaks Flaming Lasso when used on ally and can break if used on Batrider.
* Vengeful Spirit can disable Batrider's 
Blink Dagger before a fight with Wave of Terror.
Additional:
* With her Nether Swap, Vengeful Spirit can save the life of an ally who gets caught with Flaming Lasso. Nether Swap also makes it highly dangerous for Batrider to attempt a lasso, as it can lead to his own demise far behind enemy lines.
* Wave of Terror's flying vision allows Vengeful Spirit to spot Batrider trying to close in on his target with 
Firefly.
Vengeful Spirit
* Nether Swap breaks one ally out of Soulbind, and can be used to redistribute the shared damage to Vengeful Spirit herself.
Vengeful Spirit
* Nether Swap can forcibly reposition 
Sharpshooter.
Medusa
* Enchantress often has a small army of neutral creeps, allowing Medusa to hit her with a later bounce of her Mystic Snake.
Medusa
* Should Luna choose to buy Manta Style, Medusa will be able to kill illusions from them with Split Shot and 
Mjollnir, which is a common item on Medusa.
* Mystic Snake allows Medusa to easily harass Luna and steal mana from her, preventing Luna from retaliating with 
Lucent Beam.
* Medusa can survive 
Eclipse thanks to Mana Shield, which can cause Luna to struggle greatly in bursting down Medusa and force her to buy Diffusal Blade and it's upgrade 
Disperser.
* Even with Black King Bar, Medusa's Stone Gaze will still be able to disable Luna, which could even discourage her from counter-initiating with Eclipse.
Additional:
* Should Luna choose to buy Manta Style, Medusa will be able to kill illusions from them with Split Shot and Mjollnir, which is a common item on Medusa.
* Mystic Snake allows Medusa to easily harass Luna and steal mana from her, preventing Luna from retaliating with Lucent Beam.
* Medusa can survive Eclipse thanks to Mana Shield, and since Luna is not a hero that often goes for Diffusal Blade, she will struggle greatly in bursting down Medusa.
* Even with Black King Bar, Medusa's Stone Gaze will still be able to disable Luna, which could even discourage her from counter-initiating with Eclipse.
* For the same reasons, Medusa makes a very powerful ally for Luna when they are in the same team.
Vengeful Spirit
* Wave of Terror can reveal a Tinker attempting to hide in the trees and then Nether Swap and Magic Missile will both serve to interrupt/lock him down, should he attempt to town portal or reload.
Vengeful Spirit
* Nether Swap can save an ally from the Chronosphere.
Additional:
* With her Nether Swap, a well positioned Vengeful Spirit can save the life of a more important ally who gets caught in 
Chronosphere.
Vengeful Spirit
* Fragile supports who die in a few hits against Sven's high physical damage: Crystal Maiden, Vengeful Spirit, Dark Willow.
Vengeful Spirit
* With the exception of Magic Missile (unless the player takes the Level 25 Talent "Magic Missile Pierces Spell Immunity"), all of Vengeful Spirit's spells ignore Spell Immunity. This also makes her good against heroes with built-in Spell Immunity like Lifestealer or Juggernaut or heroes that tend to pick up Black King Bar, like Sven.
Medusa
* Stone Gaze allows Medusa to easily kite and kill Sven.
* Mana Shield negates much of Sven's burst damage.
Additional:
* Mana Shield makes it very hard for Sven to burst her within Storm Hammer's stun duration.
* Stone Gaze makes it very difficult for Sven to fight Medusa at any stage of the game.
* Mystic Snake can slow Sven down enough for allies to capitalize on his commitment in a fight.
Medusa
* Mana Shield can tank most of the damage from Reaper's Scythe; with sufficient mana, the kill threshold drops significantly.
* Necrophos has a movement speed equal to Medusa, and is easy to chase down with a slowing item in Medusa's inventory.
Medusa
* Her Mana Shield is too tough for Lycan to break.
* Mystic Snake can hit for a massive damage once it spread between his summons.
Additional:
* Can be easily petrified despite his speed.
* Summoned wolves will be targeted by Split Shot or Mystic Snake
Vengeful Spirit
* Vengeful Spirit has two abilities to interrupt Death Ward, even through Black King Bar.
Medusa
* Visage's familiars are easy targets to Split Shot.
* Mana Shield will resist Soul Assumption instances without effort.
Medusa
* Mana Shield makes Medusa very hard to take down in Duels.
* Stone Gaze stops Legion Commander from Dueling altogether, regardless of who she targets.
Medusa
* Split Shot can destroy Tombstone Zombies and Tombstone itself while still damaging heroes.
Medusa
* 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.
Vengeful Spirit
* 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.
Medusa
* 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.
Medusa
* Heroes with a lot of burst damage, especially those who rely on casting spells: Lina, Zeus.
Vengeful Spirit
* Vengeful Spirit can Nether Swap enemies out of Power Cogs.
Additional:
* Nether Swap gives Vengeful Spirit a way to save an ally from Clockwerk's Power Cogs.
* Magic Missile will interrupt Clockwerk trying to run down Vengeful Spirit's allies with Battery Assault.
Medusa
* Heroes that are hard to gank: Axe, Death Prophet, 
Phantom Lancer, Slark, 
Centaur Warrunner, Bristleback, Medusa, Mars.
Medusa
* 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.
Medusa
* 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.
Vengeful Spirit
* Lina can burst Vengeful Spirit down, provided she can land Light Strike Array before Vengeful Spirit lands her Magic Missile.
* 
Laguna Blade deals massive damage, often being enough to kill a squishy Vengeful Spirit.
Vengeful Spirit
* Heroes with abilities that can pull Lina out of position can easily bring her to their team mates, like Batrider with Flaming Lasso, Pudge with 
Meat Hook and Vengeful Spirit with Nether Swap.
Medusa
* Heroes with a lot of burst damage, especially those who rely on casting spells: Lina, Zeus.
Vengeful Spirit
* Heroes who relies on illusions and summons (Beastmaster, Chaos Knight, etc.).
Medusa
* Heroes with Linken's Sphere as core item: Weaver, 
Morphling, Medusa.
Vengeful Spirit
* Nether Swap triggers extra damage from Rupture.
* Blood Rite sets up while Vengeful Spirit using her Nether Swap within a timed correctly.
Medusa
* Mana Shield makes it very difficult for Bloodseeker to gain his Thirst bonuses.
* Rupture rarely kills Medusa through Mana Shield.
Medusa
* 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.
Vengeful Spirit
* Heroes with abilities that can lock down Terrorblade and prevent him from using Sunder: Bane, Batrider, Earthshaker, Elder Titan, Faceless Void, Invoker, 
Legion Commander, Mars, 
Primal Beast, Riki, Shadow Shaman, 
Silencer, Vengeful Spirit, 
Void Spirit.
Vengeful Spirit
* Magic Missile has a considerably long cast time, making it difficult to stop 
Charge of Darkness with it.
* Other than Magic Missile, Vengeful Spirit has no way of canceling 
Nether Strike.
Medusa
* If Medusa activates Stone Gaze before Spirit Breaker reaches her with Charge of Darkness, the charge will inevitably fail.
* Medusa has three ways to counter Spirit Breaker's Charge of Darkness: Stone Gaze can disable Spirit Breaker's Charge of Darkness if he faces Medusa directly. Aghanim's Scepter upgraded Mystic Snake can disable Spirit Breaker and cancel his Charge of Darkness if it hits him. And 
Cold Blooded provided by Aghanim's Shard that can cast a single-targeted Mystic Snake at Spirit Breaker if he uses Charge of Darkness on her.
* Mana Shield and overall tankiness allows Medusa to easily survive Spirit Breaker's initiation. And to make things worse, Spirit Breaker is not a common Diffusal Blade nor Disperser wielder to counter this problem at all.
* Overall, any attempt for Spirit Breaker to gank and kill Medusa will hurt him more than the other way around.
Medusa
* Other heroes who has armor and slow debuffs won't allow Medusa to disengage from combat: Tidehunter, Bristleback, Slardar.
Medusa
* Medusa cares less than other heroes about armor reduction, since Mana Shield blocks 70% of all damage without taking armor/magic resistance into consideration. This makes 60% of your Corrosive Haze ineffective until Medusa's mana is drained.
Medusa
* 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.
Vengeful Spirit
* With the exception of Magic Missile (unless the player takes the Level 25 Talent "Magic Missile Pierces Spell Immunity"), all of Vengeful Spirit's spells ignore Spell Immunity. This also makes her good against heroes with built-in Spell Immunity like Lifestealer or Juggernaut or heroes that tend to pick up Black King Bar, like Sven.
Medusa
* 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.
Medusa
* Mana Shield reduces the effectiveness of Counter Helix.
* Stone Gaze makes it very difficult for Axe to initiate on Medusa and her allies.
Vengeful Spirit
*
Vendetta disables Vengeance Aura and allows him to attack Vengeful Spirit with 
Impale and 
Mind Flare.
Spiked Carapace is easy to use against a Wave of Terror or Magic Missile.
*
Medusa
*
Vendetta burns a significant amount of mana on hit, and the damage from the ability drains Medusa's mana pool even further.
Spiked Carapace if he's within range of Medusa's abilities and isn't invisible.
Aghanim's Scepter extremely hard to deal with if Medusa is the team's main damage source.
Split Shot, Medusa can be easily interrupted by Spiked Carapace during combat, especially during her precious 
Stone Gaze.
Mana Shield, especially if Medusa only increases her mana pool by bolstering intelligence (which has the added bonus of increasing Mana Burn's damage).
Mystic Snake and 
Split Shot can trigger Spiked Carapace.
Medusa lacks single target damage, making a Burrowed Nyx Assassin hard to kill.
* Due to the passive nature of Mystic Snake and Split Shot, it can possibly proc Nyx's
* Medusa lacks single target damage, making Nyx with
Additional:
* With her passive
* Mana Burn quickly destroys
* Uncontrollable damage from
*