Venomancer
* Venomancer's damage-over-time abilities do little damage against Counterspell.
* Blink helps Anti-Mage get away from Venomancer's slows.
Additional:
* 
Counterspell provides magic resistance, diminishing the effectiveness of Venomancer's spells.
* Venomancer's lack of hard disable allows Anti-Mage to use 
Blink, circumventing the slows Venomancer depends on.
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.
Venomancer
* Sniper can easily destroy 
Plague Ward from long range.
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.
Venomancer
* Any hero that can outrange Plague Ward can neutralize them without putting themselves at risk of receiving Poison Sting: 
Arc Warden, 
Chen, 
Clinkz, 
Drow Ranger, 
Lina, 
Mirana, 
Nature's Prophet, 
Pugna and 
Sniper.
* Special mention to heroes that outrange Plague Ward after obtaining talents that increase attack range.
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.
Venomancer
* Vulnerable spellcasters with no escape mechanisms are easy targets for Huskar: 
Lich, 
Crystal Maiden, 
Silencer, 
Keeper of the Light, 
Venomancer, etc.
Additional:
* Huskar can easily regenerate lost health from DoT spells through 
Berserker's Blood rendering them ineffective
* Venomancer has little armor and mobility, and rarely builds Linken's Sphere, so he is quite vulnerable to 
Life Break.
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.
Venomancer
* 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.
Medusa
* Other heroes who has armor and slow debuffs won't allow Medusa to disengage from combat: 
Tidehunter, 
Bristleback, 
Slardar.
Venomancer
* Sunder can prevent Terrorblade's or an ally's death by swapping health, making damage-over-time abilities inefficient. Heroes that rely on damage-over-time abilities like Venomancer and 
Huskar will have a hard time against Sunder.
Additional:
* 
Reflection illusion will apply Poison Sting back towards Venomancer.
* 
Conjure Image and 
Metamorphosis will make quick work of Plague Wards.
* While ticking down from Poison Nova, Terrorblade can wait until the last possible moment to 
Sunder a target, either friend or foe.
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
* 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.
Venomancer
* While 
Reincarnation is off cooldown, Poison Nova poses less of a threat as Wraith King will return with all debuffs cleared.
* 
Vampiric Spirit can out-heal the slow {tooltip:DoT|Damage over Time} from Poison Sting.
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.
Venomancer
* Venomancer is a low health hero and low range hero who is easy to harass with Ion Shell on a creep in the early game.
* Venomancer depends entirely on all his slows to keep distance or chase, but since Surge ignores slows, it is nearly impossible for Venomancer to hunt or run away from Dark Seer or his surged teammates.
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.
Venomancer
* In the laning stage, making illusions of Venomancer will turn his 
Poison Sting back at him, making for an easy gank at level one, and for later when your mid comes for ganks.
Venomancer
* 
Corrosive Skin means Viper can often outlast Venomancer in a battle of attrition.
* Venomancer has no mobility without items, which makes him vulnerable to constant slows.
Venomancer
* Voodoo Restoration heals to counter damage over time of 
Poison Nova and Poison Sting.
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
* 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
* 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.
Venomancer
* 
Venomous Gale is a great ganking and farming skill.
* Plague Ward serves as a flexible ability for pushing, ganking, farming and scouting. The innate Poison Sting also works on the stolen Plague Ward with half the damage.
* Poison Nova, if stolen and cast, puts a huge damage-over-time debuff on the enemy team, even greater than Venomancer himself with the help of 
Arcane Supremacy.
* 
Spell Steal has a greater cast distance than the effect area of Poison Nova, allowing Rubick to steal the spell while staying at the back.
* Venomancer suffers from mana pool problems, while Rubick has relatively high intelligence gain and can cast the same set of spells at ease.
Additional:
* All of Venomancer's abilities are decent choices for Rubick's Spell Steal. Stealing Plague Wards makes them apply Poison Sting as well.
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.
Venomancer
* Venomancer's damage-over-time abilities are easier to heal through with numerous Shadow Waves than other types of damage, and it's simple to time a Shallow Grave until the last possible second to save a teammate from them.
Venomancer
* Teleportation allows Natures Prophet to save himself from the damage over time of Venomous Gale, Poison Sting and Poison Nova.
* Plague Wards can be destroyed with Nature's Prophet's Treants.
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.
Venomancer
* Snowball can be used to save allies or himself during Venomous Gale and Poison Nova.
* Venomancer lacks mobility and has low base health, so he can be killed by Walrus PUNCH!
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.
Venomancer
* Heroes that deal damage over time will also fail to bring down Abaddon and his allies, such as Huskar, Venomancer, or 
Phoenix.
Additional:
* 
Borrowed Time & 
Aphotic Shield can dispel Venomous Gale and Poison Sting.
Venomancer
* Fortune's End and False Promise easily dispel many crippling debuffs, such as Venomancer's Venomous Gale, or 
Skywrath Mage's 
Ancient Seal.
Additional:
* 
Fortune's End can dispel Venomous Gale and Poison Sting from allies.
* 
Fate's Edict grants 100% magic resistance to target, inhibiting the damage from Venomancer abilities.
Venomancer
* Any hero that can outrange Plague Ward can neutralize them without putting themselves at risk of receiving Poison Sting: Arc Warden, Chen, Clinkz, Drow Ranger, Lina, Mirana, Nature's Prophet, Pugna and Sniper.
* Special mention to heroes that outrange Plague Ward after obtaining talents that increase attack range.
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 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
* Other heroes who has armor and slow debuffs won't allow Medusa to disengage from combat: Tidehunter, Bristleback, Slardar.
Venomancer
* Any hero that can outrange Plague Ward can neutralize them without putting themselves at risk of receiving Poison Sting: Arc Warden, Chen, Clinkz, Drow Ranger, Lina, Mirana, Nature's Prophet, Pugna and Sniper.
* Special mention to heroes that outrange Plague Ward after obtaining talents that increase attack range.
Medusa
* Hard carries who just want to farm and be left alone will not appreciate Primal Beast, heroes such as Medusa, Drow Ranger...
Venomancer
* Any hero that can outrange Plague Ward can neutralize them without putting themselves at risk of receiving Poison Sting: Arc Warden, Chen, Clinkz, Drow Ranger, Lina, Mirana, Nature's Prophet, Pugna and Sniper.
* Special mention to heroes that outrange Plague Ward after obtaining talents that increase attack range.
Venomancer
* Squishy heroes or heroes without hard disables or silences: 
Shadow Demon, 
Shadow Fiend, Venomancer, 
Ancient Apparition etc.
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.
Venomancer
* Slardar can attack through Plague Wards and gain 
Bash of the Deep charges, and 
Templar Assassin can spill 
Psi Blades through Plague Wards too.
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.
Venomancer
* Any hero that can outrange Plague Ward can neutralize them without putting themselves at risk of receiving Poison Sting: Arc Warden, Chen, Clinkz, Drow Ranger, Lina, Mirana, Nature's Prophet, Pugna and Sniper.
* Special mention to heroes that outrange Plague Ward after obtaining talents that increase attack range.
Venomancer
* Venomancer has low health, which makes him vulnerable to Lina's heavy magic damage.
* Fiery Soul attack speed bonus removes Plague Wards easily in all stages of the game.
Medusa
* Heroes with a lot of burst damage, especially those who rely on casting spells: Lina, 
Zeus.
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.
Venomancer
* Heroes who rely on damage over time as Spiked Carapace can block and reflect only one instance of damage: 
Jakiro, Viper, Venomancer, Huskar, 
Ember Spirit, 
Dark Seer, 
Sand King, 
Doom, 
Dawnbreaker. However, this also means they are easily stunned.
Venomancer
* Untouchable won't mitigate Venomancer's magical damage, and Enchantress is vulnerable to magic damage.
* Both Venomous Gale and Poison Nova lower the amount of healing received by Enchantress and her allies from Nature's Attendants.
Medusa
* Enchantress often has a small army of neutral creeps, allowing Medusa to hit her with a later bounce of her Mystic Snake.
Venomancer
* Aggressively Poofing and Earthbinding is not going to end well against Venomancer, as he will be an easy target for 
Noxious Plague.
* Venomancer's constant slows greatly reduce Meepo's mobility.
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.
Venomancer
* Venomous Gale, Poison Sting and Poison Nova deal damage over time and will chip away at Gravekeeper's Cloak in addition to slowing an already sluggish hero.
* Venomancer's normal attacks deal Poison Sting and will chip away at Gravekeeper's Cloak.
Medusa
* Visage's familiars are easy targets to Split Shot.
* Mana Shield will resist Soul Assumption instances without effort.
Venomancer
* Similar to Night Stalker, Venomancer can simultaneously scout Magnus hiding in trees and put Blink Dagger on cooldown with Plague Ward, which gives Magnus problems when trying to blink in and initiate.
Additional:
* Venomancer can simultaneously scout Magnus hiding in trees and putting 
Blink Dagger on cooldown with Plague Wards, which makes Magnus real problems to blink and initiate.
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.
Venomancer
* Heroes that can slow Charge of Darkness by a huge amount: Venomancer, Viper, 
Dazzle, Arc Warden, Lion, Huskar, Shadow Shaman, 
Visage, 
Undying, Jakiro.
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.
Venomancer
* Heroes who thrive on teamfights can be a problem, such as Venomancer, 
Necrophos, 
Centaur Warrunner...
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.
Venomancer
* Any hero that can outrange Plague Ward can neutralize them without putting themselves at risk of receiving Poison Sting: Arc Warden, Chen, Clinkz, Drow Ranger, Lina, Mirana, Nature's Prophet, Pugna and Sniper.
* Special mention to heroes that outrange Plague Ward after obtaining talents that increase attack range.
Venomancer
* Venomancer's damage over time can force Chen to use Hand of God prematurely, potentially wasting a chance to save his allies during a teamfight.
* Venomancer's Poison Nova, Venomous Gale and Plague Ward can easily kill Chen's creeps.
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.
Venomancer
* Heroes that commonly attack ethereal units will not have any problems against Muerta's Pierce The Veil: 
Tinker, Jakiro, Lina, Luna, Pugna or 
Ogre Magi, Enigma, Batrider, 
Techies, 
Broodmother, Dawnbreaker, Shadow Shaman, 
Bane, Tinker, Venomancer, Arc Warden.
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.
Venomancer
* Heroes that can apply early pressure before Phantom Assassin has farm are massive threats: Axe, Viper, 
Meepo, Jakiro, Pugna, Slark, Venomancer etc.
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.
Venomancer
* Plague Wards are very hard for Batrider to play against as they provide a lot of vision as well as disable Blink Dagger for a long duration.
Venomancer
* Plague Wards may reveal a hiding Techies. If there's a sentry nearby, they may also reveal a stack of mines hidden in a juking spot.
Venomancer
* Venomancer's magical damage-over-time poisons will constantly put Tree Dance on cooldown, greatly diminishing Monkey King's mobility.
* Venomous Gale and Poison Nova will hit Monkey King when he is perched on a tree, or disguised with Mischief.
* However, Venomancer is also easily ganked by Monkey King if caught by surprise.
Additional:
* Venomancer's magical damage-over-time poisons putting 
Tree Dance on cooldown, greatly diminishing Monkey King's mobility.
* Venomous Gale and Posion Nova will hit Monkey King when he is perched on a tree, or disguised by 
Mischief.
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
* 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.
Venomancer
* Unless Puck is facing the direction he wants to blink while in Phase Shift, the Venomous Gale and Noxious Plague combo consistently ticks many times over several seconds, making it very difficult to use Blink Dagger towards the other direction. Puck's slow turning rate makes this even worse.
* Venomancer can use Plague Wards to reveal Puck's position before he even gets a chance to initiate.
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.
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.
Venomancer
* Due to lack of magic resistance, Venomancer poisons eats through Windranger's health.
Additional:
* Due to lack of magic resistance, Venomancer abilities eats through Windranger's health.
* Venomancer's multiple slows, to an extent, negates Windrun's mobility.
Venomancer
* Venomancer's slows and magical damage-over-time works well against Earthshaker's which completes lack of mobility.
* Plague Wards are useful for slowing and kitting down Earthshaker, revealing him from initiating and re-initiating and putting his Blink Dagger on cooldown if Venomancer has vision over Earthshaker.
Additional:
* Earthshaker can be kited by Venomancer's slows, which is lack of mobility.
* Plague Wards is very useful for slowing and kitting down Earthshaker, revealing him from initiating and re-initiating and putting his Blink Dagger on cooldown.
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.
Medusa
* Split Shot can destroy Tombstone Zombies and Tombstone itself while still damaging heroes.
Medusa
* Mana Shield makes it very difficult for Bloodseeker to gain his Thirst bonuses.
* Rupture rarely kills Medusa through Mana Shield.
Venomancer
* Venomancer's magical damage-over-time poisons greatly reduce Bounty Hunter's mobility.
* Venomous Gale, combined with Plague Wards and Poison Nova with True Sight items can allow Venomancer and his teammates to gank Bounty Hunter while he is roaming alone.
Medusa
* Lifestealer's low mobility makes him easy to kite.
* Stone Gaze pierces 
Rage, wasting its cooldown and making Lifestealer unable to fight.
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.
Venomancer
* Venomancer's slows and magical damage-over-time work well against Axe's complete lack of mobility.
* Plague Ward is especially useful for slowing down Axe, and revealing him before he initiates, as well as putting his Blink Dagger on cooldown.
Additional:
* Venomancer's slows and magical damage-over-time work well against Axe's complete lack of mobility.
* Plague Wards is especially useful for slowing down Axe, and revealing him before he initiates, as well as putting his Blink Dagger on cooldown.
* For the same reasons, Venomancer is a good ally for Axe when the situation is reversed.
Medusa
* Mana Shield reduces the effectiveness of Counter Helix.
* Stone Gaze makes it very difficult for Axe to initiate on Medusa and her allies.
Medusa
* Heroes with Linken's Sphere as core item: 
Weaver, 
Morphling, Medusa.
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.
Venomancer
* Venomancer's spells all deal magical damage, ignoring Bulwark.
* Venomancer's multiple slows are especially effective at kiting Mars.
* Plague Ward can attack through Arena Of Blood.
Additional:
* Venomancer's poison attacks are all magical damage, ignoring Bulwark.
* Venomancer's multiple slows are especially effective against Mars' low mobility.
* Plague Wards can attack through Arena of Blood.
Medusa
* Medusa's Stone Gaze forces Mars to choose between getting petrified, or turning his vulnerable back on Medusa.
Venomancer
* In general, heroes that can slow down Dragon Knight's movement speed will do well against him. This includes Venomancer and others in addition to the heroes mentioned above.
Medusa
* Heroes with a lot of burst damage, especially those who rely on casting spells: Lina, Zeus.
Venomancer
* Due to her slow movement speed,heroes with crowd control and slows can shut down Dawnbreaker:Lion, Crystal Maiden ,Venomancer etc.
Medusa
* Heroes that are hard to gank: Axe, 
Death Prophet, 
Phantom Lancer, Slark, Centaur Warrunner, Bristleback, Medusa, Mars.
Venomancer
* Heroes who can harass Omniknight out of lane will keep him weak in the mid game: Viper, Venomancer, Clinkz.
Venomancer
* Slardar can attack through Plague Wards and gain Bash of the Deep charges, and Templar Assassin can spill Psi Blades through Plague Wards too.
Venomancer
* Venomancer's entire arsenal deals lingering damage over a long time and therefore burns through her Refraction very quickly. Not only that, his persistent slow from Poison Sting (it can be re-applied again and again with Plague Ward) allows his team to catch up to her even with the disruption from her Psionic Trap.
Additional:
* Venomous Gale and Plague Wards allow to quickly melt through 
Refraction charges.
* Both Poison Nova and Venomous Gale hit invisible units, so 
Meld cannot be used defensively.
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.
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.
Venomancer
* Venomancer's poison damage over time is very effective against Spectre, who tends to lack magic resistance during the early to mid game.
* Venomancer's multiple slows greatly reduces Spectre's movement speed and mobility.
* Plague Wards can scout out Spectre while she is hiding in trees.
Additional:
* Venomancer's poison damage-over-time are very effective against Spectre, which is lack of magic resistance from early to mid game.
* Venomancer's multiple slows greatly reduces Spectre's low mobility, even through 
Spectral Dagger.
* Plague Wards reveals Spectre while she is hiding on trees.
Venomancer
* Heroes rely on their debuff to control the opponent will have a hard time against Press the Attack: Venomancer, 
Earth Spirit, Ogre Magi
Additional:
* 
Press the Attack dispels Venomous Gale and Poison Sting from Legion Commander or her teammates.
* Venomancer is an ideal target for 
Duel due to his lack of mobility and low starting health.
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.
Venomancer
* 
Dark Rift allows Underlord to transport allies from poison damage-over-time to the fountain.
* Underlord usually buys 
Pipe of Insight that gives a magic resistance to allies, inhibiting the damage from Venomancer abilities.
Venomancer
* 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
* 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.
Venomancer
*
Dark Pact can dispel Venomous Gale and Poison Sting.
Shadow Dance allows Slark heightened regeneration when out of vision making DoTs effects less threatening.
*
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.