* Heroes with summons: Lycan, Broodmother, Visage, Nature's Prophet, Warlock.

* Lifestealer's low mobility makes him easy to kite.
* Stone Gaze pierces Rage, wasting its cooldown and making Lifestealer unable to fight.

* Once you get a Black King Bar, squishy spellcasters like Zeus, Skywrath Mage and others will be probably easy to deal with.

* Heroes with a lot of burst damage, especially those who rely on casting spells: Lina, Zeus.

* Illusion and heroes with summons are difficult to kill with Chen's single-target offensive spells: Terrorblade, Phantom Lancer, Chaos Knight, Broodmother, Naga Siren, Lycan, Visage. And even though Chen can convert enemy summons with Holy Persuasion, their much greater numbers will often overwhelm Chen and his creeps.

* Heroes with strong area-of-effect damage can make quick work of Chen's converted creeps and at same time gain farm: Magnus, Jakiro, Shadow Fiend, Kunkka, Luna, Dragon Knight, Medusa, Alchemist.

* 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.

* Howl reduces a good chunk of Marci's attack damage that she relies heavily on, and the armor reduction works better on her because of her low armor.
* Shapeshift renders Lycan immune to slow from Rebound and Unleash.

* If Medusa activates Stone Gaze, the charge will inevitably fail.
* Mana Shield and overall tankiness allows Medusa to easily survive Spirit Breaker's initiation.

* He can send wolves to defuse Proximity Mines, and he can catch up Techies and kill him before they can deny themselves. Even if the suicide is successful, Lycan can still survive because of his tankiness.

* Shapeshift allows Lycan to chase down Earth Spirit.

* 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 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.

* Shapeshift increases Lycan's movement speed and renders him unslowable, allowing him to easily avoid and escape Ancient Apparition's abilities.
* Lycan has fast summons, both his wolves from Summon Wolves can do heavy damage to Ancient Apparition due to his immobility and low armor.

* Mana Shield tanks 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.

* Shapeshift allows Lycan to escape from Upheaval with maximum movement speed.
* Warlock doesn't have a good solution to deal with Lycan's wolves from Summon Wolves.

* Lycan doesn't care much about Lich's slows thanks to Shapeshift.
* Chain Frost can bounce to the wolves that Lycan summons.
Additional:
* Lich possesses a lot of slows, which Lycan doesn't care about when he Shapeshifts.
* Lich has no in-built escape, which makes him a good target for Lycan.

* Void's slow is useless against Lycan by activating Shapeshift.
* Night Stalker's single target abilities (with the exception of Void upgraded by Aghanim's Scepter) is not very effective against Lycan's Summon Wolves during the early and mid game.

* Split Shot can destroy Tombstone Zombies and Tombstone itself while still damaging heroes.

* Mirana's Leap is ineffective if Lycan uses Shapeshift. It also allows him to dodge Sacred Arrow.

* Visage's familiars are easy targets to Split Shot.
* Mana Shield will resist Soul Assumption instances without effort.

* 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.

* Heroes with haste can negate Enchant's slow: Weaver, Dark Seer, Lycan, Centaur Warrunner.

* Enchantress often has a small army of neutral creeps, allowing Medusa to hit her with a later bounce of her Mystic Snake.

* Lycan and Weaver has abilities that allow them to move at maximum movement speed, and those abilities can't be dispelled, potentially wasting the slow from Demonic Purge.

* Multiple attackers thanks to summoned units or clones: Meepo, Witch Doctor, Lycan, Enigma, Shadow Shaman
* Heroes that can quickly deal damage to her, regardless of how weak they are, can easily break through her Refraction:
* Multiple attackers thanks to summoned units or clones: Meepo, Witch Doctor, Lycan, Enigma, Shadow Shaman
* Multiple attackers thanks to illusions: Phantom Lancer, Chaos Knight, Naga Siren (bonus for her Ensnare). Also despite the visual effects, Templar Assassin does not spill damage against illusions or buildings, so she is not a really good hero to clean up illusions.
* Weak damage but high tick rate or persist in a long time: Slark, Gyrocopter, Queen of Pain, Shadow Shaman (Shackles), Jakiro, Pugna

* Heroes with single-target abilities will be overwhelmed by Lycan and his summons: Wraith King, Bane, Phantom Assassin.

* Heroes who do not have nor rely on passive abilities make Nethertoxin much less effective: Clinkz, Pugna, Nature's Prophet, Dark Seer, Lycan, Tusk

* Once you get a Black King Bar, squishy spellcasters like Zeus, Skywrath Mage and others will be probably easy to deal with.

* Heroes with a lot of burst damage, especially those who rely on casting spells: Lina, Zeus.

* 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.

* Heroes with both illusions and summons, for Io has nothing to deal with multiple enemies at once outside from Spirit's weak area-of-effect: Broodmother, Chaos Knight, Lycan, Naga Siren, Nature's Prophet, Phantom Lancer, Shadow Shaman, Terrorblade, Visage, Warlock.

* Heroes with low armor and little mobility, like Huskar, Io, etc. will also have an unfortunate fate.

* 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.

* A Lycan with Shapeshift can always run down Puck for a very quick kill due to its low armor. It is important to abuse as many cliffs and trees as possible to escape from a Lycan.

* Mana Shield reduces the effectiveness of Counter Helix.
* Stone Gaze makes it very difficult for Axe to initiate on Medusa and her allies.

* Shapeshift allows Lycan to get close and disable Marksmanship.
* Shapeshift also makes him immune to slows like Drow Ranger's Frost Arrows.
Additional:
* The Wolves' speed causes the knockback from Gust to be ineffective.
* She lacks escapes and loses her Marksmanship when someone is near her. Lycan takes advantage of these weaknesses.

* Mana Shield makes Medusa very hard to take down in Duels.
* Stone Gaze stops Legion Commander from Dueling altogether, regardless of who she targets.

* The movement speed granted from Shapeshift means that Spectre has no way to punish Lycan if he wants to splitpush or pick off supports. Furthermore, he will kite Haunt and cannot be slowed by Spectral Dagger.
* Lycan is often part of an early game push strategy which is often the best counter to Spectre because she needs a lot of time and space to come online as a late game carry.

* Heroes with single-target abilities will be overwhelmed by Lycan and his summons: Wraith King, Bane, Phantom Assassin.

* Heroes with disables that ignore spell immunity will render Phantom Assassin quite useless in teamfights throughout the game: Axe, Enigma, Vengeful Spirit, Doom, Bane, Beastmaster, Pudge, Medusa.

* Heroes who can summon illusions and summons because Terrorblade has no abilities to deal with multiple enemies at once outside Reflection: Shadow Shaman, Naga Siren, Broodmother, Lycan, Enigma, Chaos Knight, Phantom Lancer, Shadow Demon, Dark Seer, Nature's Prophet, Invoker, Morphling, Visage, Grimstroke with Aghanim's Scepter.

* 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 manfight Medusa at any stage of the game.
* Mystic Snake can slow Sven down enough for allies to capitalise on his commitment in a fight.

* Mana Shield makes it very difficult for Bloodseeker to gain his Thirst bonuses.
* Rupture rarely kills Medusa through Mana Shield.

* 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.

* Lycan's high HP easily shrug off Nyx Assassin's burst damage and fend him off.

* 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.

* Lycan's ultimate makes him immune to slows from Ursa's Earthshock as well as allowing him to outmaneuver Ursa during Enrage. Lycan can also easily chase down Ursa while shapeshifted, should Ursa try to flee.

* Shapeshift is useful for killing or escaping Silencer.
* Summon Wolves, can be used to hunt and harass silencer - even when Lycan himself can't fight.

* 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.