Medusa
* 
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.
Additional:
* 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.
Primal Beast
* Like above, supports with reliable stuns can be a massive problem and force 
Black King Bar in fights unideally, such as 
Shadow Shaman, 
Lion, 
Nyx Assassin.
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.
Primal Beast
* Like above, supports with reliable stuns can be a massive problem and force Black King Bar in fights unideally, such as Shadow Shaman, Lion, Nyx Assassin.
Primal Beast
* 
Borrowed Time allows him to both exit his stuns prematurely and turn Trample into healing for himself. His Aghanim Scepter only prevents the automation of the spell, Abaddon himself can still manually activate it.
* 
Aphotic Shield will immediately debuff any stuns Primal Beast has put on allies but won't stop him from being stunned if casted on Abaddon.
Primal Beast
* Oracle can negate and shut down Primal Beast simply with Fate's Edict, especially in the early game, as a majority of his damage-dealing spells are magic.
* Oracle can interrupt Primal Beast's 
Onslaught charge with a well-timed Fortune's End.
* Primal Beast's lethal burst damage combos can be further stalled with False Promise; combined with Fate's Edict and regen from Purifying Flames, Oracle can even completely negate Primal Beast's offense.
Additional:
* 
Fate's Edict completely negates all of Primal Beast's major damage-dealing spells in the early game and can render Primal Beast useless when cast on a target he is focusing, or in Oracle's defense against Primal Beast himself.
* 
Fortune's End keeps Primal Beast in place, especially while trampling or in the middle of an Onslaught charge.
* 
False Promise can interrupt Primal Beast's abilities, as well as further delay Primal Beast from dealing lethal burst damage. In combination with Fortune's End, Oracle can potentially save an ally from Primal Beast's spell combos.
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.
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
* 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.
Primal Beast
* 
Power Cogs keeps Primal Beast pinned down, preventing him from doing damage with Trample. Primal Beast's slow attack speed makes it hard for him to break the cogs and get away. In addition, Power Cogs' knockback is forced movement and thus will intercept Primal Beast's Onslaught if placed well.
* 
Battery Assault on a lone Primal Beast in the early game effectively keeps him from winding up Onslaught or basic attacking.
* 
Rocket Flare and 
Jetpack (from purchasing 
Aghanim's Shard) give Clockwerk many options to scout for Primal Beast, whose kit benefits greatly from ambushing.
Primal Beast
* 
Shukuchi allows Weaver to have faster movement speed and can outrun Primal Beast in most instances, such as while he is trampling.
* Trample disarms Primal Beast, so casting 
The Swarm can make him vulnerable to ranged attacks. Primal Beast also has an innately slow attack speed and will take a long time destroying the bugs.
* 
Time Lapse allows Weaver to negate and heal burst damage, which Primal Beast is reliant on.
Primal Beast
* 
Glimpse can prevent Primal Beast from initiating for most of the game with Onslaught.
* While 
Static Storm is not much of a threat in terms of damage, it does prevent Primal Beast from casting any spells for a long period of time if also trapped in 
Kinetic Field.
* Overall, Disruptor forces Primal Beast to buy a Black King Bar much earlier than he might like but becomes a major threat to Disruptor once he does.
Primal Beast
* Primal Beast is disarmed during Trample so will be unable to destroy a 
Supernova no matter how close it is to him.
* The same ability can also be used to save allies with the help of an Aghanim's Scepter.
* 
Sun Ray will do thousands of damage to Primal Beast if surviving a full channel time due to his high health scaling for the ability.
* 
Icarus Dive is a fantastic way to escape Primal Beast after he has used Onslaught.
* Phoenix has a naturally very high health pool making it hard for Primal Beast to deal with him with his magical damage.
Primal Beast
* The ensnare from melee 
Berserker's Rage can prevent Primal Beast from dealing further Trample damage and can allow Troll Warlord to relentlessly build 
Fervor on him.
* 
Whirling Axes (Ranged) can slow down Primal Beast while trampling and allow Troll Warlord to better control him from range.
* 
Whirling Axes (Melee) can blind Primal Beast if he attempts to auto-attack Troll Warlord after a fully charged Uproar.
* 
Battle Trance will make Primal Beast a sitting duck should he be rooted and attacked to death.
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.
Primal Beast
* 
Time Walk makes it impossible for Primal Beast to stay on top of Faceless Void with his abilities and allows him to heal burst damage dealt to him.
* Once Faceless Void has an Aghanim's Shard, Onslaught can be easily escaped. He could also choose to get a lower cooldown on Time Walk, making it even harder for Primal Beast to catch him in fights or stop his initiations.
* 
Time Dilation will make Primal Beast useless for an extended time after casting his abilities if he does not have a dispel.
* 
Chronosphere has many uses such as stopping Primal Beast from casting abilities on him or allies or even on a teammate, since Primal Beast has no way to assist allies trapped within the sphere.
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.
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.
Primal Beast
* 
Soulbind prevents Primal Beast from being able to use Onslaught or his abilities to great effect for a lengthy amount of time.
* 
Phantom's Embrace is very difficult for Primal Beast to remove due to his slow attack speed and Trample preventing him from attacking.
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.
Primal Beast
* Supports who can slow him to the point Trample does very little damage in the lane are also not fun: 
Lich, 
Ogre Magi, 
Winter Wyvern.
Primal Beast
* Primal Beast is mostly played in the offlane role, so picking a carry who can escape from him is essential. Heroes such as 
Troll Warlord, 
Lone Druid and 
Outworld Destroyer, or generally any carry with a stun, slow or ability to fight back will stop him from having the good start he needs.
Primal Beast
* Like above, supports with reliable stuns can be a massive problem and force Black King Bar in fights unideally, such as Shadow Shaman, Lion, Nyx Assassin.
Primal Beast
* Supports who can slow him to the point Trample does very little damage in the lane are also not fun: Lich, Ogre Magi, Winter Wyvern.
Primal Beast
* Primal Beast is mostly played in the offlane role, so picking a carry who can escape from him is essential. Heroes such as Troll Warlord, Lone Druid and Outworld Destroyer, or generally any carry with a stun, slow or ability to fight back will stop him from having the good start he needs.
Primal Beast
* Primal Beast really suffers against supports he cannot bully in the lane: this includes 
Dazzle, 
Shadow Demon and 
Dark Willow since they can use their respective abilities to stop Primal Beast from dealing burst damage, or make it hard for him to stay in range.
Primal Beast
* Any ganking heavy support can be a big problem for Primal Beast, such as: 
Earth Spirit, 
Grimstroke before he has a Black King Bar.
Primal Beast
* Supports who can slow him to the point Trample does very little damage in the lane are also not fun: Lich, Ogre Magi, Winter Wyvern.
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.
Primal Beast
* Primal Beast really suffers against supports he cannot bully in the lane: this includes Dazzle, Shadow Demon and Dark Willow since they can use their respective abilities to stop Primal Beast from dealing burst damage, or make it hard for him to stay in range.
Medusa
* Other heroes who has armor and slow debuffs won't allow Medusa to disengage from combat: 
Tidehunter, 
Bristleback, 
Slardar.
Primal Beast
* Primal Beast really suffers against supports he cannot bully in the lane: this includes Dazzle, Shadow Demon and Dark Willow since they can use their respective abilities to stop Primal Beast from dealing burst damage, or make it hard for him to stay in range.
Medusa
* Other heroes who has armor and slow debuffs won't allow Medusa to disengage from combat: Tidehunter, Bristleback, Slardar.
Primal Beast
* 
Pit of Malice is very good at preventing Primal Beast from entering the fight and stopping Trample damage at all stages of the game.
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.
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.
Primal Beast
* Any hero with low mobility and max healthsuch as 
Silencer, Crystal Maiden etc.
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
* 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.
* For the same reasons, Medusa makes a very powerful ally for Luna when they are in the same team.
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.
Primal Beast
* Primal Beast has a massive healthpool making it very difficult to get through it with a nuke such as Eclipse or Lucent Beam.
* Primal Beast is faster than Luna, as one of her main ways to escape danger, is very problematic for her in the laning stage especially.
* His ultimate goes through debuff immunity, making Luna's Black King Bar less effective.
* Primal Beast commonly buys 
Blade Mail which is a big problem for a single target bursting hero like Luna.
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.
Primal Beast
* 
Pierce the Veil does not prevent Primal Beast from using any of his spells to their fullest and is one of the few heroes that can disable her during her ultimate and a common Black King Bar purchase. She will also likely be fatal to herself if Primal Beast has a Blade Mail active.
* 
Gunslinger will be disabled if Primal Beast buys an Aghanim's Scepter.
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.
Primal Beast
* Magnus is not tanky and struggles against burst damage, something Primal Beast excels at in the early-to-mid game. Primal Beast is also able to out-damage Magnus's 
Empower and can even contribute to his Uproar stacks.
* Using 
Skewer to drag Primal Beast while he is trampling will count as movement and will trigger a rapid number of slams, which could prove lethal to Magnus.
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.
Primal Beast
* Heroes who rely on burst damage with magical damage will struggle to kill Primal Beast: 
Spirit Breaker, Gyrocopter, 
Leshrac
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.
Primal Beast
* Phantom Assassin is known to be weak against bursts of magical damage, something Primal Beast excels at from the beginning of the game. He can use this to his advantage by constantly hunting Phantom Assassin down, especially if she is left alone to farm.
* Primal Beast is a good carrier of 
Ethereal Blade, 
Vanguard and 
Shiva's Guard all of which are very good against 
Coup de Grace and 
Phantom Strike.
* Even though Primal Beast does a lot of physical damage early on, later once 
Blur becomes more potent, she may find herself being overwhelmed by Trample and Onslaught instead.
* Primal Beast's ultimate goes through spell immunity and his level 25 talent makes it even more devistating against Phantom Assassin.
* Primal Beast can dispel 
Stifling Dagger and any attack modifers it applies with his left level 15 talent.
Medusa
* Lifestealer's low mobility makes him easy to kite.
* Stone Gaze pierces 
Rage, wasting its cooldown and making Lifestealer unable to fight.
Primal Beast
* Special mention to 
Lifestealer who can use Rage to prevent Trample damage, but Primal Beast's ultimate can still be casted during the spell.
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.
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.
Medusa
* Enchantress often has a small army of neutral creeps, allowing Medusa to hit her with a later bounce of her Mystic Snake.
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.
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.
Primal Beast
* Illusion heroes will struggle against Primal Beast's area damage capability, such as 
Chaos Knight, Naga Siren, Terrorblade.
Primal Beast
* 
Sprout gets destroyed by Trample and Onslaught.
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
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.
Primal Beast
* Primal Beast has multiple ways to cancel 
Life Drain very quickly.
* Pugna has a very low strength gain and as a support does not have much gold to buy health items, making him vulnerable to Primal Beast's onslaught of magical damage.
* Ironically, 
Decrepify actually just increases Primal Beast's damage on the targeted ally if Trample is activated. However, it can be used to slow him down and prevent any further Trample damage.
Primal Beast
* Since Primal Beast is highly mobile with Onslaught alone, he will be difficult to catch with both 
Cold Feet and Ice Blast.
* Ice Blast is less effective due to Primal Beast's massive health pool and resistance to taking damage.
* While 
Chilling Touch can be used to slow Primal Beast briefly, it is not enough to beat him back, and can also contribute to his Uproar stacks.
* Primal Beast has a dispel talent at level 15 that will remove Cold Feet immediately when Uproar is used.
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.
Medusa
* Split Shot can destroy Tombstone Zombies and Tombstone itself while still damaging heroes.
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
* 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
* Visage's familiars are easy targets to Split Shot.
* Mana Shield will resist Soul Assumption instances without effort.
Medusa
* Heroes with Linken's Sphere as core item: 
Weaver, 
Morphling, Medusa.
Primal Beast
* Any hero who lanes very poorly will struggle with Primal Beast's potential snowball in the very early levels, like Keeper of the Light, Luna, 
Templar Assassin...
Primal Beast
* Heroes who rely on burst damage with magical damage will struggle to kill Primal Beast: Spirit Breaker, Gyrocopter, Leshrac
Medusa
* Heroes with a lot of burst damage, especially those who rely on casting spells: Lina, Zeus.
Primal Beast
* Illusion heroes will struggle against Primal Beast's area damage capability, such as Chaos Knight, Naga Siren, Terrorblade.
Primal Beast
* Any hero with low mobility and max healthsuch as Silencer, Crystal Maiden etc.
Primal Beast
* Heroes who have low or high armor but very high health will be difficult for drow to burst down quickly: 
Primal Beast, Axe, 
Centaur Warrunner.
Primal Beast
* Heroes who cannot escape from Trample early might be easy first blood. Heroes like 
Witch Doctor and Omniknight should play very cautiously alone...
Primal Beast
* Heroes who rely on burst damage with magical damage will struggle to kill Primal Beast: Spirit Breaker, Gyrocopter, Leshrac
Medusa
* Heroes that are hard to gank: Axe, Death Prophet, 
Phantom Lancer, Slark, Centaur Warrunner, Bristleback, Medusa, Mars.
Medusa
* Heroes with a lot of burst damage, especially those who rely on casting spells: Lina, Zeus.
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.
Primal Beast
* Long lockdown is a great way to deal with Axe to prevent Berserker's Call from being used, heroes such as 
Legion Commander, Beastmaster and Primal Beast are good examples of this.
Additional:
* Berserker's Call will be a stun for Primal Beast and not much else due to Trample making him unable to attack.
* 
Battle Hunger is neglitable because Primal Beast has a much bigger health than Axe, so he does not need to fear being slowed, or his other abilities including 
Counter Helix or even a Blade Mail.
* Getting Primal Beast low enough to use a successful Culling Blade can be very difficult due to his massive health advantage over most heroes.
* Not ability related but Primal Beast does not need to fear Axe in lane, as Trample, combined with Uproar and Onslaught will do a ton of damage even if Axe has a Vanguard.
Primal Beast
* Heroes who cannot escape from Trample early might be easy first blood. Heroes like Witch Doctor and Omniknight should play very cautiously alone...
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.
Primal Beast
* Terrorblade has no stun and is vulnerable to Primal Beast's spell comboes due to his low health points in the laning stage and mid game.
* 
Reflection can be dispelled using Primal Beast's level 15 left talent.
* 
Sunder is the only real threat Terrorblade has against Primal Beast but he may die before he can even use it.
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.
Primal Beast
* 
Dispersion reduces damage based on a percentage, which is very minimal against large amounts of small instances of damage such as Trample. It reduces each tick by about 14 at the maximum level, which is very small.
* 
Desolate is never a threat to Primal Beast due to his large health pool and Uproar is still out-damaging the ability.
* Onslaught can allow Primal Beast to chase Spectre fleeing with 
Spectral Dagger, as both skills phase through trees and terrain.
* Primal Beast can also dispel Spectral Dagger's slow with his left level 15 talent, making it completely useless against him.
* Primal Beast excels at early aggression, pushing weak carries out of lane and farming areas he wants to control. Overall just not a pleasant matchup for Spectre.
* Should Primal Beast buy an Aghanim's Scepter he can also break both passive abilities.
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.
Primal Beast
* Primal Beast can use Uproar to tank a portion of 
Omnislash, making him much more likely to survive it. Primal Beast can also charge away from Omnislash using Onslaught as the spell ends.
* 
Blade Fury will never do more damage than Uproar once the stacks are activated.
* Primal Beast is very commonly buying items that are good against Juggernaut, such as Ethereal Blade and 
Heart of Tarrasque.
* Primal Beast has one of the few ultimates that can prevent Juggernaut from spinning away with a teleport.
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.
Primal Beast
* Primal Beast is one of Sniper's greatest counters, as he has no real means of escape and is very squishy, especially in the early game. Sniper's potshots and 
Shrapnel can contribute to Primal Beast's Uproar and further make him tankier than he already is. Onslaught allows him to close the gap on Sniper at his own volition, and Trample can deal serious damage to his meager health pool.
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 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.
Primal Beast
* Any hero who lanes very poorly will struggle with Primal Beast's potential snowball in the very early levels, like Keeper of the Light, Luna, Templar Assassin...
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.
Primal Beast
* Dark Pact, 
Shadow Dance and 
Depth Shroud will do nothing against Onslaught and Trample, as they are both ground area-of-effect spells.
* Primal Beast has a gigantic hitbox, which could be difficult for Slark to escape with 
Pounce should Primal Beast choose to block him. Pounce also does not completely prevent Primal Beast from trampling offensively, as he still has some room to move.
* Primal Beast has a huge health pool making it difficult to shed it with Essence Shift and may allow Primal Beast to build Uproar stacks against him very rapidly.
* If Primal Beast buys an Aghanim's Scepter he can also break Essence Shift from working on attacks which is a big part of Slark's damage output.
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.
Primal Beast
* Onslaught prevents all of Razor's abilities from being effective against him, especially in the laning stage.
Primal Beast
* 
Malefice will prevent Primal Beast from doing anything for a long duration even in the early game when at his strongest.
* Midnight Pulse will scale with his max health so will do a ton of damage combined with any generic stun or Enigma's own abilities.
* Primal Beast relies completely on mobility to do damage, Black Hole makes sure he cannot use any abilities or threaten heroes he is typically good against.
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.
Primal Beast
* Primal Beast's abilities require movement to deal damage, making 
Rupture potentially deadly and debilitating. Furthermore, its initial damage based on the target's current health is devastating to a full-health Primal Beast with his high strength gain and thus high HP.
* Due to his reliance on spells, Primal Beast is vulnerable to Blood Rite's powerful silence without items to counter it.
Medusa
* Mana Shield makes it very difficult for Bloodseeker to gain his Thirst bonuses.
* Rupture rarely kills Medusa through Mana Shield.
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.
Primal Beast
* While Broodmother can hide in the trees with Spin Web, Primal Beast's ability to trample trees down can give him an edge in catching her.
* 
Insatiable Hunger will not do much vs Primal Beast's onslaught of disables.
* While Silken Bola can slow Primal Beast down, it's not enough to stop Trample from doing more damage than Broodmother can do back.
* 
Spawn Spiderlings will be destroyed by Onslaught and Trample very easily.
Primal Beast
* Heroes who can do scaling health damage to Primal Beast are very threatening for the hero. Such as: Phoenix, 
Tinker etc.
Primal Beast
* Heroes with unorthodox escapes will struggle against Primal Beast, such as 
Nature's Prophet, Tinker, and Templar Assassin.
Medusa
* E.M.P. allows Invoker to burn Medusa's mana to weaken
Mana Shield.
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's lack of mobility makes her easy to kite with Invoker's spells.
Additional:
*
*
*
Primal Beast
* Invoker's numerous area-of-effect abilities can interrupt Primal Beast, especially while he is in the middle of a team fight, where Primal Beast thrives. (
Tornado, 
Cold Snap, and 
Ice Wall all help to disable Primal Beast and control him from a distance.
E.M.P. disintegrates Primal Beast's low mana pool.
Black King Bar.
*
* However, Invoker is quite a slow-paced hero and not particularly known for being survivable against a rampaging Primal Beast with