* Disruption will save Shadow Demon's teammates from being killed by Counter Helix or Culling Blade.
* Soul Catcher and Shadow Poison can put Axe's Blink Dagger on cooldown.
* Demonic Purge slows Axe to a crawl, making him nearly useless after initiating. If Shadow Demon has Aghanim's Scepter, it will also break Counter Helix.

* Mystic Snake can harass Axe in lane and drain his small mana pool.
* Mana Shield reduces the effectiveness of Counter Helix.
* Stone Gaze makes it very difficult for Axe to pursue.

* Mana Shield tanks most of the damage from Reaper's Scythe; with sufficient mana, the kill threshold drops to 15%/17%/19% health (before reductions).
* Heartstopper Aura does not chip away at Medusa's mana, this makes it not a threat as it deals damage based on current health.
* Necrophos has a movement speed equal to Medusa, and is easy to chase down with a slowing item in Medusa's inventory.

* Disruption can save an ally from a fatal Reaper's Scythe.
* Demonic Purge can remove Ghost Shroud, making Necrophos vulnerable to physical damage and preventing him from regenerating health.

* Heroes that lose a great amount of damage output and become less threatening: Phantom Assassin, Sven, Slark, Phantom Lancer.
* Once you have an Aghanim's Scepter, Shadow Demon instantly reaches a new power spike and becomes a counter for a variety of heroes that have strong passives.
* Heroes that lose a great amount of their tankiness and become easier to finish off: Bristleback, Spectre, Phantom Assassin, Enchantress, Dragon Knight.
* Heroes that lose a great amount of damage output and become less threatening: Phantom Assassin, Sven, Slark, Phantom Lancer.
* You can always stack camps and farm the scepter with Shadow Poison.

* Stone Gaze allows Medusa to easily kite and kill Sven.
* Mystic Snake eats away at Sven's small mana pool.
* Mana Shield negates much of Sven's burst damage.

* Heroes with break can disable Untouchable for a while: Doom and Shadow Demon (via Aghanim's Scepter), Viper

* Enchantress often has a small army of neutral creeps, allowing Medusa to hit her with a later bounce of her Mystic Snake.
* Untouchable is ignored by secondary attacks from Split Shot.

* Melee carries such as Sven, Ursa or Lifestealer can be slowed and easily kited with Demonic Purge.

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

* Heroes with ways to protect themselves or allies from Spirit Breaker's initiation: Shadow Demon

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

* Stone Gaze negates Dispersion's damage reduction and allows Medusa to kite Spectre.
* Spectre's small mana pool is depleted quickly by Mystic Snake.
* Split Shot can clear Haunt illusions quickly.

* Her illusions with Desolate are very valuable, especially when they are usually paired with Radiance. Unlike blink or force movement, Spectral Dagger's escaping mechanic requires manual movement, and therefore Demonic Purge can hold her back really hard and allow your allies to finish her off.
* If she tries to kill you or any key ally with Haunt at any point of the game, remember to not panic and always use Disruption on the illusion, whether it is fake or the real Spectre herself. When the situation calls, Demonic Purge can save a second victim from a haunting Spectre.
* When upgraded by Aghanim's Scepter, Demonic Purge can remove Spectre from a fight by disabling Desolate and Dispersion, negating her damage and tankiness respectively.

* Medusa's Stone Gaze forces Mars to choose between getting petrified, or turning his vulnerable back on Medusa.

* Heroes with break abilities: Nyx Assassin, Shadow Demon (with Aghanim's Scepter), Viper.

* Disruption can banish Faceless Void or an ally in Chronosphere, making it less effective of an ability.
* Faceless Void's illusions created by Disruption will not get stunned by Chronosphere, allowing Shadow Demon to attack Faceless Void in his Chronosphere.
* Casting Disruption after releasing Shadow Poison charges will make Time Walk unable to backtrack the damage.
* Shadow Poison is a good way to deal damage as the initial damage and the release damage can't both be Time Walked at the same time.
* Demonic Purge is a great slow, useful to force out a Time Walk early and can break Time Lock with Aghanim's Scepter.

* 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.

* Disruption instantly removes Phantom Embrace, and can potentially save allies affected by Soulbind.
* Demonic Purge dispels Ink Swell.

* Heroes who can hide the Dueled target (Outworld Destroyer, Shadow Demon, Tusk, Phoenix with Aghanim's Scepter etc).

Additional:
* Disruption can save allies and mess up an initiation from an enemy Legion Commander. Using Disruption on your ally that is affected by Duel will leave her totally exposed without the benefit of the life steal from Moment of Courage. A precise decision to Disrupt Legion Commander or her victim is crucial to waste Duel's potential.
* Demonic Purge cannot be dispelled by a hard dispel from Press the Attack, which in turn can be dispelled by your ultimate.

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

* Shadow Demon's spammable illusions can be used to scout Techies' Proximity Mines. The illusion of your carries can be even used to trick Techies into detonating his precious Remote Mines.

* 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.

* 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.

* Split Shot can destroy Tombstone Zombies and Tombstone itself while still damaging heroes.
* Mana Shield reduces the impact of Decay and Flesh Golem's Plague Aura.

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

* Shadow Demon can waste precious seconds of Windrun with Disruption.
* Alternatively, Demonic Purge can be used to dispel it altogether, leaving her completely defenseless for 7 seconds.
* Disruption can be used to save an ally if they get stunned by Shackleshot.

* The constant dispel from Demonic Purge will make any attempt to save the victim or himself by Surge become futile. For what it's worth, Demonic Purge will also dispel Ion Shell.

* Alchemist is a well-known Radiance carrier among other auras your illusions will benefit from. They also get the extra move speed and reduced base attack time from his Chemical Rage, and it's even better if you can catch him as his own rage is about to expire.
* Disruption will buy enough time for all allies to retreat when Alchemist starts to activate Unstable Concoction.

* Summoned gargoyles will give Medusa free target practice.
* Mana Shield will resist Soul Assumption instances without effort.

* 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.
* Mystic Snake can be potentially detrimental to Enigma's initiation. Getting hit by the latter high-damage bounces (from standing behind his Eidolons or his teammates) can hinder his mana pool, preventing him from executing a strong initiation.
Additional:
* Mana Shield makes Medusa harder to kill with Enigma's Black Hole and Pulse combo.
* Medusa's Split Shot can kill Demonic Conversion creeps easier and Mystic Snake bounces off from them.
* Stone Gaze makes it hard for Enigma to approach Medusa for a Black Hole.

* Similarly, they can negate your X Marks The Spot & Torrent combo by protecting your target when you use Return. Good candidates to negate your combo include Outworld Destroyer and his Astral Imprisonment, and Shadow Demon and his Disruption.
* Heroes with hide abilities can often dodge a Ghostship just before it hits.
* Similarly, they can negate your X Marks The Spot & Torrent combo by protecting your target when you use Return. Good candidates to negate your combo include Outworld Destroyer and his Astral Imprisonment, and Shadow Demon and his Disruption.
* A Eul's Scepter of Divinity can also do the trick, but, unlike the previously mentioned abilities, you can only use it on yourself and not your allies.

* Doom, Disruptor with Aghanim's Scepter, and hex abilities all prevent item usage, which is a severe problem for Phantom Assassin as it prevents her from using Black King Bar, the one item that helps protect her against the aforementioned dangers. Doom and Shadow Demon with Aghanim's Scepter also disables Phantom Assassin's Evasion and Critical Strike, removing much of her damage and survivabaility.

* Heroes with high physical damage output but lack of reliable escape mechanisms are always a good target for a solo gank: Sniper, Shadow Fiend, Troll Warlord, Drow Ranger. Those heroes, however, are dangerous if they manage to close the gap, so take caution.

* Heroes that lose a great amount of their tankiness and become easier to finish off: Bristleback, Spectre, Phantom Assassin, Enchantress, Dragon Knight.
* Once you have an Aghanim's Scepter, Shadow Demon instantly reaches a new power spike and becomes a counter for a variety of heroes that have strong passives.
* Heroes that lose a great amount of their tankiness and become easier to finish off: Bristleback, Spectre, Phantom Assassin, Enchantress, Dragon Knight.
* Heroes that lose a great amount of damage output and become less threatening: Phantom Assassin, Sven, Slark, Phantom Lancer.
* You can always stack camps and farm the scepter with Shadow Poison.

* Heroes that create illusions (such as Spectre, Shadow Demon, Phantom Lancer, Naga Siren, Chaos Knight, Terrorblade) or bring other units into the fight (such as Nature's Prophet, Lone Druid, Chen, Enchantress and the aforementioned Meepo and Arc Warden) can cause Eclipse to strike the illusions/summons unintentionally. (However, in many cases Moon Glaives can resolve this issue and eliminate them before activating Eclipse).

Additional:
* Demonic Purge takes off Luna's superior mobility, removing the need for chasing her and allowing your team to reposition in team fights or escape when at low HP. If Shadow Demon has Aghanim's Sceptre it will also take away glaive bounces and extra damage from Luna's passive.
* Luna's illusions created by Disruption are very valuable with their Moon Glaives. These will effectively counter her pushing attempts and are painfully effective in team fights.
* Disruption can be used to save an ally from Eclipse.

* Heroes with high physical damage output but lack of reliable escape mechanisms are always a good target for a solo gank: Sniper, Shadow Fiend, Troll Warlord, Drow Ranger. Those heroes, however, are dangerous if they manage to close the gap, so take caution.

* Heroes with cleave abilities and 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.

* Heroes with abilities that break Berserker's Blood, lowering Huskar's attack speed and health regeneration: Doom, Shadow Demon, Viper.

* Heroes that can punish aggressive heroes, such as: Leshrac, Shadow Demon, Pugna, Death Prophet.

* Heroes with Linken's Sphere as core item: Weaver, Morphling, Medusa.

* Heroes that can gain vision over trees to catch Tinker: Invoker, Shadow Demon, Batrider

* Disruption can protect Shadow Demon's allies from Fortune's End, preserving healing or buffs. It can also catch Oracle's allies, allowing Shadow Poison and Soul Catcher to be used without being dispelled.
* Demonic Purge prevents over-time healing during False Promise, such as Purifying Flames and Urn of Shadows. If he has Aghanim's Scepter, this issue can persist for longer or on multiple allies.
* It will not, however, prevent healing from instant abilities, items, or auras, making Mekansm a good choice against him.

* Shadow Demon with an Aghanim's Scepter will use Demonic Purge to disable Curse of Avernus and the passive component of Borrowed Time. If this is combined with a silence, Borrowed Time will not trigger at all.
* Even without Aghanim's Scepter, he can still waste Borrowed Time with Disruption. Curse of Avernus fully works on illusions, turning the passive ability against him.

* Her Mana Shield is too tough for Lycan to break in.
* 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

* Poof won't damage Medusa and he can Gaze an entire flock of Meepos.
* Mystic Snake will easily become the bane of Meepo early game.

* Shadow Demon's Soul Catcher hinders Bristleback's tanking capabilities. Demonic Purge with Aghanim's Scepter disables Bristleback's passives.

* Heroes that can dominate his illusions or create their own illusions of him: Dark Seer, Morphling, Enchantress, Shadow Demon.

* Shadow Demon, Outworld Destroyer and Tusk can all save a Lasso'd teammate with their defensive spells.

* Heroes with high physical damage output but lack of reliable escape mechanisms are always a good target for a solo gank: Sniper, Shadow Fiend, Troll Warlord, Drow Ranger. Those heroes, however, are dangerous if they manage to close the gap, so take caution.

* Heroes that can purge buffs can dispel Guardian Angel: Invoker, Shadow Demon, Oracle.

Additional:
* Demonic Purge can dispel Guardian Angel on the key target during combat, allow your allies to finish them.

* Disruption sets up Anti-Mage for a chain disable. The illusions will deal extra damage due to Mana Break.
* Soul Catcher causes Anti-Mage to take a large chunk of damage, and can hit him when he is inside from Disruption.
* Shadow Poison hits Anti-Mage even after he's Blinked away.
* If Shadow Demon managed to get Aghanim's Scepter, Demonic Purge will disable Anti-Mage's passive skills, making him more vulnerable and it cannot be dispelled.
Additional:
* While it is unwise to encounter Anti-Mage alone, Disruption's considerable cast range can become a perfect setup for any hard-disable to follow up. If he is pinned down, Anti-Mage will quickly face his demise when the illusions deplete his already low mana pool. Manta Style will easily allow him to escape, however.
* The illusions can be controlled to quickly sap mana from any other target, making Anti-Mage one of the most valuable targets to disrupt.

* 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.

* Heroes with summons or illusions makes Sacred Arrow harder to land: Shadow Demon, Phantom Lancer, Nature's Prophet.

* Heroes with abilities that can save teammates are also effective such as Shadow Demon, Dazzle, Oracle, Bane, Pugna, Tusk, Winter Wyvern, Io, Underlord, Treant Protector and Keeper of the Light.

Additional:
* Be ready to save an ally from Omnislash with your Disruption.
* Spawning Juggernaut's illusions is a great deal, as his base attack time is low and he has a critical strike. Illusions will benefit from both.
* Demonic Purge will prevent Juggernaut's desperate attempt to flee using Blade Fury. However, it cannot stop him if he is using Town Portal Scroll.