* His global teleportation with Boots of Travel and Rearm is easily countered with Haunt, and Spectre can reach him anywhere on the map.
* He is squishy, and if alone Desolate will kill him very fast.
* Laser's blind isn't reliable, since Desolate cannot miss.

* Spectre can use Haunt to intercept and disrupt Magnus's initiation attempts.
* Spectral Dagger can severely slow down Magnus after he uses Skewer.
* Magnus often travels alone when he is trying to initiate, so Desolate can be very effective against him.
Additional:
* Spectre disables Magnus' Blink Dagger using her ultimate, and later into the game can usually outlive Reverse Polarity's duration.

* Zeus can easily find Magnus who is often hiding in the trees with Thundergod's Wrath and Lightning Bolt, which allows him to warn allies and disrupt his initiation attempts.

* Due to Tinker's low health pool, Zeus can easily burst Tinker down, while also cancelling Rearm.
* Once Zeus gets Aghanim's Scepter, he will gain Nimbus, which allows him to scout out Tinker on the map, especially when he is pushing lanes while hiding in the trees.
Additional:
* Zeus can easily reveal Tinker's location in the trees with Thundergod's wrath.
* When Zeus has an Aghanim's Scepter, he can use his Nimbus, together with Lightning Bolt to interrupt Tinker's Boots of Travel channelling and cancel Tinker's Blink Dagger.

* Night Stalker can easily find Tinker in the trees during Dark Ascension.
* Void's mini-stun will stop Rearm and Boots of Travel.
* Crippling Fear's silence will prevent Tinker from fighting back, as Tinker relies on his spells.
Additional:
* Night Stalker is one of the best heroes to find (and silence) Tinker in the trees during Dark Ascension.

* Dark Ascension reduces vision for the enemy team, which makes it more difficult for Magnus to initiate with Blink Dagger and Reverse Polarity. It is also more likely that Night Stalker will scout out Magnus with Aghanim's Scepter and a Gem of True Sight, after which he can silence Magnus with Crippling Fear.

* 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.

* Nether Ward discourages Tinker from using abilities and items due to its high damage against heavy mana usage.

* Pounce prevents Tinker from blinking away.
* Slark frequently builds Shadow Blade, which allows him to approach Tinker unnoticed. Since Tinker's farming usually covers a significant amount of area on the map, Sentry Wards may not be cost effective.
* Shadow Dance allows Slark to detect both common and unusual wards. Eliminating common ward causes Tinker trouble farming many lanes if he does not know who may be waiting to jump on him. Slark is also uniquely able to identify some of the less common wards used by Tinker, such as those placed on the cliffs at map edges which Tinker uses to give him vision over the trees he uses to hide in.
* Slark's extremely high move speed from Shadow Dance, potentially stacked with Shadow Blade, allows him to easily follow Tinker between lanes, especially if Tinker has pushed the lanes out.
* Dark Pact dispels Laser's blind.

* Heroes with blink or movement abilities, which are disabled by Pounce's leash: Anti-Mage, Earth Spirit, Faceless Void, Magnus, Mirana, Monkey King, Morphling, Pangolier, Phantom Assassin, Phoenix, Puck, Queen of Pain, Riki, Sand King, Spirit Breaker, Timbersaw, Tusk.

* Anti-Mage's high mobility from Blink and tendency to build Battle Fury makes him strong against split-pushing heroes: Nature's Prophet, Tinker, and Arc Warden.

Additional:
* Tinker is fragile and vulnerable against carries like Anti-Mage.
* Mana Break burns away his mana pool and deals bonus physical damage.
* Tinker's massive mana pool makes Mana Void deal large amount of damage, and can be used to cancel a Boots of Travel teleport even through spell immunity.
* Blink gives Anti-Mage many options, like disjointing Heat Seeking Missiles or leaving March of Machines' area of effect. He can use Blink to wait out of sight for a split pushing Tinker or chase a blinking Tinker into trees.
* Tinker doesn't want any of his spells reflected back at him through Counterspell.

* Heroes who build mana boosting items but have low mana regeneration are especially vulnerable against Mana Break and Mana Void: Timbersaw, Slark, Shadow Fiend, Clinkz, Bristleback Nyx Assassin, Magnus

* 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.

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

* 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.

* Similarly, heroes with low cooldown teleports can be afraid to split push against X Marks the Spot, such as Tinker and Nature's Prophet.
* In general, highly mobile heroes like Earth Spirit or Storm Spirit are at a disadvantage against X Marks the Spot.
* Similarly, heroes with low cooldown teleports can be afraid to split push against X Marks the Spot, such as Tinker and Nature's Prophet.

Additional:
* X Marks the Spot can be used to prevent Tinker from escape with Blink Dagger or Boots of Travel, discourage him from snapping farm and snapping gank. However, in later game, it'll be much more difficult because Tinker can buy Black King Bar or Linken's Sphere to prevent Kunkka from placing X on him, or Eul's Scepter of Divinity to prevent the recall

* Rocket Flare can find Tinker if he blinks into the treeline, and Hookshot will prevent him from teleporting out.
* Battery Assault makes Tinker unable to Rearm by stunning him repeatedly.
Additional:
* Clockwerk can easily catch a split pushing Tinker with his Hookshot and prevent him from escaping with Power Cogs and Battery Assault.
* He can find a Tinker hiding in trees with his Rocket Flare.
* Clockwerk usually buys a Blade Mail, which does lots of damage to Tinker if he gets hit by his abilities (especially March of the Machines).

* Wave of Terror can reveal a Tinker attempting to hide in the trees and then Nether Swap and Magic Missile will both serve to interrupt/lock him down, should he attempt to town portal or reload.

* Treant Protector can usually scout out Magnus in the trees with Eyes in the Forest and disrupt his initiation attempts. He can also counter Magnus' initiation with Overgrowth.

* Most of Magnus' abilities except Empower will trigger damage through Corrosive Skin.
* Poison Attack and Viper Strike can slow Magnus during Skewer, as well as putting his Blink Dagger on cooldown, preventing him from initiating or re-initiating.

* His whole skillset acts like a counter to Tinker:
* Impale prevents Tinker from blinding Nyx Assassin or fighting back, while giving Nyx' allies time to catch up to Tinker's position.
* Mana Burn generally deals more damage to intelligence based heroes like Tinker
* Spiked Carapace can stun Tinker at a moment of Nyx Assassin's choosing if March of the Machines has been cast. It is also quite easy to time Spiked Carapace against Heat Seeking Missiles.
* Vendetta allows Nyx to approach Tinker in the trees or wait for him in common hiding spots and deal heavy damage to his low armor.
Additional:
* March of the Machines and Heat-Seeking Missile allow easy Spiked Carapace stuns.
* As a fragile hero that relies on mana and intelligence items, Tinker is vulnerable to Mana Burn.
* Nyx Assassin's stuns can interrupt Rearm and leave Tinker helpless.

* Tinker relies on his high mobility from Boots of Travel and Blink Dagger to survive. Those items don't help him if Spirit Breaker manages to cast Charge of Darkness on him.
* Spirit Breaker can easily cancel Rearm and Boots of Travel.

* If Luna can use Eclipse in anticipation, Magnus will be killed before he can even manages to cast Reverse Polarity.
* Aghanim's Scepter upgraded Eclipse is a very good counter-initiation tool against Magnus when he casts Reverse Polarity, granted as long as Luna can cast it from safe distance.

* Luna can easily prevent Tinker from escaping with Boots of Travel or Rearm with Lucent Beam.
* Luna can also quickly tear Tinker to shreds with Eclipse as soon as he jumps in with Blink Dagger.

* 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.
Additional:
* 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.

* Phoenix will usually be on the sidelines or further back ready to use Sun Ray. Even after Magnus successfully uses Reverse Polarity and skewer Phoenix's teammates, Phoenix can usually counter-initiate using all of its abilities.

* Tinker is an easy target for Earth Spirit to initiate on. He likes to split push lanes once he acquieres Boots of Travel and Earth Spirit can jump him with his Rolling Boulder and disable him to buy enough time for his teammates to come and assist Earth Spirit.
* The huge range of Stone Remnant and Rolling Boulder enables Earth Spirit to stop Tinker from teleporting to his fountain since Tinker tends to buy Blink Dagger most of the time to escape.

* As Tinker relies heavily on his spells to be effective, Last Word and Global Silence will render him largely useless.
* Arcane Curse effectively prevents Tinker from casting spells during its duration, as he will otherwise suffer heavy damage.
* Glaives of Wisdom deal pure damage, which make quick work of fragile heroes like Tinker.
Additional:
* Silencer can stop Rearm, preventing Tinker from spamming his abilities/items or escaping.

* Storm Spirit destroys trees and ignores impassable terrains with Ball Lightning, rendering them dangerous places for Tinker to hide within.
* Ball Lightning disjoints projectile from Heat-Seeking Missile and damage from March of the Machines.
* Electric Vortex prevents Tinker from teleporting away, and Static Remnant and Overload can easily burst him down.
Additional:
* He can easily catch Tinker in the trees with Ball Lightning and kill him with Orchid Malevolence and his abilities, which deal both physical and magical damage, making them difficult for Tinker to itemize against.

* Press the Attack can dispel Laser's blind while providing great attack speed and health regeneration.
* Once caught in a Duel, Tinker, who completely relies on his spells to be effective, has little chances of survival with his low health pool and armor.

* Magnus has very mediocre damage against Alchemist, because he can survive the stun duration of Reverse Polarity with Chemical Rage.

* Shadow Wave provides good sustain against Tinker's spammable abilities.
* Shallow Grave can stop Tinker from bursting down a target.

* Tinker is heavily reliant on casting his spells and Doom can disable all of his abilities and items. An Aghanim's Scepter only makes it harder for Tinker to survive.
Additional:
* Tinker is heavily dependent on active abilities and Doom prevents him from using any of them.

* Disruptor can disable Magnus's Blink Dagger using Thunder Strike during a considerable duration, disrupting his initiation attempts.
* Glimpse brings Magnus back after he escapes with Skewer and/or Force Staff.
* Static Storm if used on a fight can prevent Magnus from using Reverse Polarity after he jumps in.

* Rubick can turn around entire teamfights if he manages to steal Reverse Polarity.
* Shockwave allows Rubick to farm pretty fast together with Fade Bolt, and also deals decent AoE damage in teamfights.
* If Rubick steals Skewer, he can use Telekinesis to displace enemies and Skewer them away.
Additional:
* All of Magnus's spells are perfect for Rubick to steal, especially Reverse Polarity for a counter-initiation.
* Telekinesis is one of the best instant-disables in the game, completely ruining Magnus's initiation.

* He can Meat Hook a Tinker hiding in the trees and follow it up with Dismember and Rot for an easy solo kill, as Tinker doesn't tend to buy survivability items.
* His innate magic resistance and huge health pool from Flesh Heap makes it hard for Tinker to deal serious damage to Pudge.
Additional:
* Meat Hook can used to pull Tinker while he is hiding in the trees, and a follow up with Dismember and Rot leads to an easy solo kill, as Tinker doesn't buy many survivability items.
* Flesh Heap makes it hard for Tinker to deal serious damage.

* 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.

* 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.

* 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.

* 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.

* Heroes that wish to disrupt fights with spell combos or big ultimates are vulnerable to the long stun of Fiend's Grip: Disruptor, Death Prophet, Enigma, Faceless Void, Invoker, Lich, Magnus, Mars, Medusa, Outworld Devourer, Phoenix, Puck, Queen of Pain, Shadow Fiend, Treant Protector, Underlord, Winter Wyvern, Witch Doctor, Zeus.

* Any hero who can survive Magnus's initiations and manfight him: Huskar, Faceless Void, Weaver, Abaddon, Troll Warlord, Alchemist, Dragon Knight, Night Stalker, Viper.

* 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.

* Heroes who take a long time to become strong are in for a rough mid game, such as Outworld Devourer, Magnus, Medusa, and Anti-Mage.

* 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.

* 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.

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

Additional:
* Tinker is relatively helpless against Invoker, as his Rearm and Boots of Travel can be easily interrupted by Invoker's long range disables, even if he blinks away.

* 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.

* 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.

* Illusion heroes, such as Naga Siren, Phantom Lancer, Chaos Knight, Terrorblade will become strong against Tinker in the late game when Tinker's only area of effect damage, March of the Machines, ceases to kill illusions quickly. Without Aghanim's Scepter Tinker is forced to defensively disarm heroes with Laser, leaving illusions free to deal physical damage which Tinker's low armor makes highly effective. In addition, Mjollnir or Battle Fury, two common pickups against illusion heroes, don't work well on Tinker at all.

* 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.

* Any hero who can survive Magnus's initiations and manfight him: Huskar, Faceless Void, Weaver, Abaddon, Troll Warlord, Alchemist, Dragon Knight, Night Stalker, Viper.

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

* Any hero who can survive Magnus's initiations and manfight him: Huskar, Faceless Void, Weaver, Abaddon, Troll Warlord, Alchemist, Dragon Knight, Night Stalker, Viper.

* Any hero who can survive Magnus's initiations and manfight him: Huskar, Faceless Void, Weaver, Abaddon, Troll Warlord, Alchemist, Dragon Knight, Night Stalker, Viper.

* Low health spellcasters: Lina, Witch Doctor, Tinker, Keeper of the Light, all rely heavily on their spells and are fragile heroes. They all also have avoidable spells, allowing Puck to get to them and quickly burst them down.

* 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.

* Plasma Field can slow Magnus during Skewer, and when combined with Eye of the Storm, will potentially disable his Blink Dagger, preventing him from initiating.
* Static Link drains the bonus damage from Empower. However, it can be broken by Skewer and/or Force Staff.
* Storm Surge gives Razor and his allies high mobility needed to avoid Shockwave & Reverse Polarity.

* Beastmaster's Hawk can find Tinker easily while he is pushing or blinking into trees.

* Magnus cannot manfight Huskar even with Empower, Berserker's Blood's high attack speed and health regeneration, combined with Huskar's high health and Burning Spear stacks will allow Huskar to kill Magnus before he can kill him.
* From a safe distance, Huskar can surprise and counter Magnus's initiation with Life Break and Burning Spear.
* Burning Spear also deals damage over time, disabling Blink Dagger and preventing him from initiating or escaping.

* Jakiro's abilities deal damage over time, which can disrupt Magnus's attempts to initiate with Blink Dagger and Reverse Polarity.
* Macropyre not only disables Blink Dagger for a considerable duration, but can also destroy Trees, revealing Magnus's cover and position.

* A common playstyle among Tinkers is to teleport to a lane creep using Boots of Travel and immediately blink into the trees to cast March of the Machines. If Techies can predict where said Tinker would blink after teleporting, he could place strategic Proximity Mines or even Remote Mines in those places. Stasis Traps also prevent Tinker from blinking or teleporting away.

* Even if Wraith King dies after Magnus disables him, Magnus' entire team will be slowed and vulnerable for counter-initiation.

* Shrapnel can sometimes scout out Magnus and also place his Blink Dagger on cooldown. Aside from that, Sniper likes to stay far back behind enemy lines, so it's difficult to catch him with Reverse Polarity unless you already have vision on him and can Skewer him to the rest of his team.