Undying
* Phantom Lancer's many illusions will easily destroy 
Tombstone, provided he has sufficient farm.
* He also has no ways of dealing with the illusions, since Decay doesn't steal strength from illusions.
Io
* Heroes with both illusions and summons, for Io has nothing to deal with multiple enemies at once outside from Spirits's weak area-of-effect: 
Beastmaster, 
Broodmother, 
Chaos Knight, 
Lycan, 
Naga Siren, 
Nature's Prophet, 
Phantom Lancer, 
Shadow Shaman, 
Terrorblade, 
Visage, 
Warlock, 
Wraith King.
Undying
* Terrorblade can destroy Tombstone with his 
Conjure Image and 
Metamorphosis.
Io
* Terrorblade can easily take advantage of Io's weak durability with 
Reflection and Metamorphosis.
* As Io relies on boosting his and his 
Tethered target's attack speed with 
Overcharge, Terrorblade can take advantage of this with Reflection, which can damage and slow both, Io and his Tethered target.
* 
Spirits's weak area-of-effect makes it a bad tool to deal with Terrorblade's illusions from Conjure Image and 
Manta Style.
* Io's damage output is one of the weakest, therefore Terrorblade will have plenty of time to save himself with 
Sunder.
* However, Terrorblade has no way of stopping Io to escape with Tether or to stop both, Io and it's Tethered target to escape with 
Relocate besides 
Terror Wave from 
Aghanim's Scepter.
Additional:
* Terrorblade can easily take advantage of Io's weak durability with Reflection and Metamorphosis.
* As Io relies on boosting his and his Tethered target's attack speed with Overcharge, Terrorblade can take advantage of this with Reflection, which can damage and slow both, Io and his Tethered target.
* Spirits's weak area-of-effect makes it a bad tool to deal with Terrorblade's illusions from Conjure Image and Manta Style.
* Io's damage output is one of the weakest, therefore Terrorblade will have plenty of time to save himself with Sunder.
* However, Terrorblade has no way of stopping Io to escape with Tether or to stop both, Io and it's Tethered target to escape with Relocate besides Terror Wave from Aghanim's Scepter.
Undying
* Sniper can easily destroy Tombstone from long range.
Io
* 
Take Aim and 
Assassinate allow Sniper to reach Io even if it stays in the backline.
Io
* Heroes with high mobility can approach Sniper: 
Anti-Mage, 
Earth Spirit, 
Io, Nature's Prophet, 
Pangolier, 
Puck, 
Queen of Pain and most notably 
Riki.
Undying
* Familiars will easily be able to kite heroes with a short range or with low attack speed. For example, 
Tiny and 
Undying have a very hard time killing Familiars.
Io
* Heroes with both illusions and summons, for Io has nothing to deal with multiple enemies at once outside from Spirits's weak area-of-effect: Beastmaster, Broodmother, Chaos Knight, Lycan, Naga Siren, Nature's Prophet, Phantom Lancer, Shadow Shaman, Terrorblade, Visage, Warlock, Wraith King.
Undying
* Chaos Knight's multiple illusions from 
Phantasm can destroy Undying, as Soul Rip can't offset the damage from the high amount of damage from his illusions.
Io
* Heroes with both illusions and summons, for Io has nothing to deal with multiple enemies at once outside from Spirits's weak area-of-effect: Beastmaster, Broodmother, Chaos Knight, Lycan, Naga Siren, Nature's Prophet, Phantom Lancer, Shadow Shaman, Terrorblade, Visage, Warlock, Wraith King.
Undying
* 
Invoker's multiple spells can lock down Undying and disable him from doing much.
Io
* Heroes whose abilities can affect multiple enemies at once: 
Dawnbreaker, 
Ember Spirit, 
Lina, 
Luna, 
Jakiro, 
Leshrac, Invoker.
Undying
* 
Death Prophet is able to 
Silence Undying up to 6 seconds. Besides, due to Undying's high strength during a team fight, 
Spirit Siphon is a powerful ability against Undying thanks to the percentage health drain.
Io
* Heroes that are hard to gank: 
Axe, Death Prophet, Phantom Lancer
Io
* 
Living Armor can be used to save a hero from a Relocate gank.
Io
* 
Phantom Strike allows Phantom Assassin jump directly to Io.
* 
Coup de Grace can make a short work of Io's low health and armor.
Io
* 
Burning Barrage and 
Searing Arrows allow Clinkz to quickly kill Io due to its low armor.
* Clinkz iz a hero that very often goes for 
Orchid Malevolence, and its upgrade 
Bloodthorn. Alternatively, Clinkz also loves to buy 
Gleipnir. And if Clinkz has both of them, he will be able to root and silence Io and prevent him from escaping with either Tether or Relocate.
Io
* Jakiro's area-of-effect ability arsenal allows him to affect multiple heroes at once, giving Io difficulties in saving them as he can only heal one hero at a time with Tether.
* 
Ice Path can be used to cancel both, Tether and Relocate.
* Jakiro commonly buys 
Rod of Atos that can be used to cancel Relocate, prevent Io in escaping with Tether and make Io easy target for Ice Path and 
Macropyre.
Additional:
* Jakiro's area-of-effect ability arsenal allows him to affect multiple heroes at once, giving Io difficulties in saving them as he can only heal one hero at a time with Tether.
* Ice Path can be used to cancel both, Tether and Relocate.
* Jakiro commonly buys Rod of Atos that can be used to cancel Relocate, prevent Io in escaping with Tether and make Io easy target for Ice Path and Macropyre.
Undying
* Necrophos is a dangerous opponent to go against with. Regardless of how much strength Undying has gained from Decay, Necrophos can finish off Undying with 
Reaper's Scythe once Undying's HP falls below a certain threshold.
* 
Heartstopper Aura will do more damage to Undying if he gained strength from Decay, as it does damage based on a hero's maximum health.
Undying
* Due to Fervor and Battle Trance, Troll Warlord has a significant attack speed, enabling him to crush Tombstone quickly.
* Undying usually stays at the front line with no disables, making him an easy target for Troll Warlord.
Io
* 
Ensnare and 
Song of the Siren can be used to cancel both, Tether and Relocate and to close the distance on Io.
* 
Rip Tide combined with illusions from 
Mirror Image often finish off Io before he can save himself.
* Spirit's weak area-of-effect makes it a bad tool to deal with Naga Siren's illusions from Mirror Image.
* Once Naga Siren buys Aghanim's Scepter, she can gain access to 
Reel In, which not only allows her to cancel both, Tether and Relocate, but also to pull Io to herself and her team while he is affected with Ensnare, similarly to Batrider's 
Flaming Lasso.
* 
Aghanim's Shard upgraded Song of the Siren can also heal the hero Io and his tethered targed try to gank.
Additional:
* Ensnare and Song of the Siren can be used to cancel both, Tether and Relocate and to close the distance on Io.
* Rip Tide combined with illusions from Mirror Image often finish off Io before he can save himself.
* Spirits's weak area-of-effect makes it a bad tool to deal with Naga Siren's illusions from Mirror Image.
* Once Naga Siren buys Aghanim's Scepter, she can gain access to Reel In, which not only allows her to cancel both, Tether and Relocate, but also to pull Io to herself and her team while he is affected with Ensnare, similarly to Batrider's Flaming Lasso.
* Aghanim's Shard upgraded Song of the Siren can also heal the hero Io and his tethered targed try to gank.
Io
* Ice Blast prevents Io from healing an ally with Tether and prevents healing from Overcharge
* Io is a common 
Mekansm builder which is useless if he is affected by Ice Blast.
Additional:
* 
Ice Blast prevents Io from healing the target.
* Ancient Apparition can easily harass Io on lane with 
Chilling Touch due to it's high range and damage. This can get even worse if Ancient Apparition buys Aghanim's Scepter and combines it with items that can give him bonus attack damage and attack speed.
* Chilling Touch combined with 
Ice Vortex makes it nearly impossible for Io to escape from 
Cold Feet. Ice Vortex can also make Io and it's tethered target more vulnerable to Ancient Apparition and his allies's magical damage.
Undying
* Zombies summoned from Tombstone will amplify the damage of 
Echo Slam due to them increasing the echo damage.
Undying
* 
Arcane Curse can effectively discourage Undying from casting his spammable abilities in a team fight, as Undying will have to suffer more damage and the slow due to the penalty duration of Arcane Curse.
* 
Last Word and 
Global Silence are able to silence Undying for up to 6 seconds, preventing Undying from gaining strength and healing his ally or himself.
Undying
* Geminate Attack works on Tombstone, allowing Weaver to kill it quickly.
* Zombies attacking Weaver disappear once he goes invisible with Shukuchi.
* Undying has no way to catch a mobile Weaver.
Undying
* Flak Cannon rips through Tombstone's zombies.
Additional:
* 
Flak Cannon enables Gyrocopter to clear the zombies easily.
Io
* Lich's 
Chain Frost forces Io to either give up providing buff to his ally with Tether or suffer devastating damage with his tethered ally.
* Lich can easily use 
Sinister Gaze to disable Io from getting away with Tether or Relocate.
Io
* Grimstroke can catch Io and his ally easily with 
Soulbind as Io has a tendency to tether himself with an ally frequently.
* Io is highly vulnerable to disables. Hence, Grimstroke's 
Phantom's Embrace is a great ability to hinder Io's potential.
Additional:
* Soulbind can target both Io and its Tethered ally, allowing Grimstroke and his team to target both with single target spells. Should Io try to Relocate, Phantom's Embrace can stop its channel to prevent escape.
Io
* 
Thirst allows Bloodseeker to see where Io relocated to, should either Io or the tethered hero have low health.
* 
Rupture forces Io to stay in place, preventing it from using the Tether bonus movement speed to escape.
Undying
* Chemical Rage will take down Tombstone in no time.
Additional:
* With 
Greevil's Greed, Alchemist can farm Tombstone zombies and gain a significant gold advantage.
Undying
* Lifestealer is able to endure Undying, especially in the laning phase, where Undying is strongest. Feast can offset 
Decay's strength steal for its percentage lifesteal. Rage delays Undying from stealing strength and can help Lifestealer destroy Undying's Tombstone uninterrupted. As well, none of Undying's abilities pierce magic immunity.
Undying
* Tombstone's zombies rarely inhibit Anti-Mage, as he can either Blink away or onto the Tombstone and destroy it.
Io
* Lightning Storm will usually hit both Io and his Tethered target since both will be close enough for the lightning to jump. It can then be followed up by Split Earth.
* Diabolic Edict and Pulse Nova hit all units near Leshrac, meaning he can do colossal damage to Io and his Tethered target.
Additional:
* Io is a hero who needs to be close to it's tethered target to make it effective, and that's where Leshrac gets the advantage thanks to many of his area-of-effect abilities.
* 
Lightning Storm will usually hit both Io and its tethered target since both will be close enough for the lightning to jump.
* 
Diabolic Edict and 
Pulse Nova hit all units near Leshrac, meaning he can do colossal damage to both, Io and its tethered target.
Io
* Disruptor can always Glimpse back Io or his target after he Relocated nearby.
* Even better, thanks to the indicator on the ground, you can even preemptively drop Static Storm and Kinetic Field on the spot they will relocate to.
* Thunder Strike and Glimpse are also good tools to bring back an Io that Tethered away in the fog of war.
Additional:
* 
Glimpse directly negates Relocate.
* 
Kinetic Field prevents Io from escaping with Tether.
* 
Static Storm can silence and damage both, Io and it's tethered target. And it can also mute both, Io and it's tethered target when upgraded with Aghanim's Scepter
Undying
* Tidehunter takes close to no damage from Undying's zombies once he maxes out his 
Kraken Shell, especially if he gets the level 20 Kraken Shell upgrading talent. This might allow him to blink away to safety.
Undying
* Split Shot can destroy Tombstone Zombies and Tombstone itself while still damaging heroes.
Undying
* All abilities from Undying easy to steal to Rubick with 
Spell Steal.
Additional:
* Tombstone can be stolen to counter-initiate the enemy team in skirmishes.
* Tombstone provides vision over the enemy around, use this to Rubick's advantage for more spells.
* Since Undying is melee and has low attack speed, the tombstone can be hard to taken down by Undying himself.
* 
Flesh Golem provides Rubick with increased Health pool and a powerful attack modifier.
* 
Rubick can apply the Flesh Golem debuff much more easily as a ranged hero.
* Decay is a decent damaging ability, making Rubick somewhat tankier in teamfights.
* 
Soul Rip can be used for extra heal or burst damage.
Io
* Batrider's Flaming Lasso can be used to cancel Io's attempts to escape with Relocate and drag him away from his Tethered target. And since Io doesn't like buying 
Linken's Sphere, he will be always vulnerable to Batrider's initiations.
* Io's tendency to stick close to it's Tethered target can make Io and it's target vulnerable to Batrider's harrasing.
* Aghanim's Scepter upgraded Flaming Lasso allows Batrider to catch and drag two heroes at once, not just one. Which can potentially turn Io's Tether against him.
Additional:
* Batrider's Flaming Lasso can be used to cancel Io's attempts to escape with Relocate and drag him away from his Tethered target. And since Io doesn't like buying Linken's Sphere, he will be always vulnerable to Batrider's initiations.
* Io's tendency to stick close to it's Tethered target can make Io and it's target vulnerable to Batrider's harrasing.
* Aghanim's Scepter upgraded Flaming Lasso allows Batrider to catch and drag two heroes at once, not just one. Which can potentially turn Io's Tether against him.
Io
* Heroes with either magical, physical or pure damage burst: 
Bane, Ember Spirit, Leshrac, Lina, Luna, 
Nyx Assassin, 
Phantom Assassin, 
Skywrath Mage, 
Tinker, 
Ursa, 
Void Spirit.
Io
* Heroes with either magical, physical or pure damage burst: Bane, Ember Spirit, Leshrac, Lina, Luna, Nyx Assassin, Phantom Assassin, Skywrath Mage, Tinker, Ursa, Void Spirit.
Io
* Heroes with low armor and little mobility, like 
Huskar, Io, etc. will also have an unfortunate fate.
Undying
* Huskar's huge damage output and attack speed can get rid of Undying and Tombstone quickly.
Io
* Heroes with both illusions and summons, for Io has nothing to deal with multiple enemies at once outside from Spirits's weak area-of-effect: Beastmaster, Broodmother, Chaos Knight, Lycan, Naga Siren, Nature's Prophet, Phantom Lancer, Shadow Shaman, Terrorblade, Visage, Warlock, Wraith King.
Io
* Heroes with both illusions and summons, for Io has nothing to deal with multiple enemies at once outside from Spirits's weak area-of-effect: Beastmaster, Broodmother, Chaos Knight, Lycan, Naga Siren, Nature's Prophet, Phantom Lancer, Shadow Shaman, Terrorblade, Visage, Warlock, Wraith King.
Io
* Heroes with both illusions and summons, for Io has nothing to deal with multiple enemies at once outside from Spirits's weak area-of-effect: Beastmaster, Broodmother, Chaos Knight, Lycan, Naga Siren, Nature's Prophet, Phantom Lancer, Shadow Shaman, Terrorblade, Visage, Warlock, Wraith King.
Io
* Heroes with either magical, physical or pure damage burst: Bane, Ember Spirit, Leshrac, Lina, Luna, Nyx Assassin, Phantom Assassin, Skywrath Mage, Tinker, Ursa, Void Spirit.
Io
* Heroes that can easily bypass Io's allies to get to Io: Riki, 
Tusk, 
Clinkz, 
Sniper, 
Slark, Phantom Assassin, Void Spirit, 
Storm Spirit, Ember Spirit, Earth Spirit, 
Spirit Breaker.
Io
* Heroes with both illusions and summons, for Io has nothing to deal with multiple enemies at once outside from Spirits's weak area-of-effect: Beastmaster, Broodmother, Chaos Knight, Lycan, Naga Siren, Nature's Prophet, Phantom Lancer, Shadow Shaman, Terrorblade, Visage, Warlock, Wraith King.
Io
* Fragile heroes: Bounty Hunter has decent nuking capabilities with Shiruken Toss and Jinada thus making fragile heroes easy picks for ganking. Few examples of such heroes are:
Crystal Maiden, 
Pugna, Skywrath Mage, Io, 
Witch Doctor, etc.
Io
* Heroes whose abilities can affect multiple enemies at once: Dawnbreaker, Ember Spirit, Lina, Luna, Jakiro, Leshrac, Invoker.
Io
* Heroes that are hard to gank: Axe, Death Prophet, Phantom Lancer
Io
* Heroes with either magical, physical or pure damage burst: Bane, Ember Spirit, Leshrac, Lina, Luna, Nyx Assassin, Phantom Assassin, Skywrath Mage, Tinker, Ursa, Void Spirit.
Io
* Heroes that can easily bypass Io's allies to get to Io: Riki, Tusk, Clinkz, Sniper, Slark, Phantom Assassin, Void Spirit, Storm Spirit, Ember Spirit, Earth Spirit, Spirit Breaker.
Io
* Heroes that can easily bypass Io's allies to get to Io: Riki, Tusk, Clinkz, Sniper, Slark, Phantom Assassin, Void Spirit, Storm Spirit, Ember Spirit, Earth Spirit, Spirit Breaker.
Io
* Heroes with either magical, physical or pure damage burst: Bane, Ember Spirit, Leshrac, Lina, Luna, Nyx Assassin, Phantom Assassin, Skywrath Mage, Tinker, Ursa, Void Spirit.
Io
* Heroes with either magical, physical or pure damage burst: Bane, Ember Spirit, Leshrac, Lina, Luna, Nyx Assassin, Phantom Assassin, Skywrath Mage, Tinker, Ursa, Void Spirit.
Io
* Heroes with either magical, physical or pure damage burst: Bane, Ember Spirit, Leshrac, Lina, Luna, Nyx Assassin, Phantom Assassin, Skywrath Mage, Tinker, Ursa, Void Spirit.
Io
* Heroes that can easily bypass Io's allies to get to Io: Riki, Tusk, Clinkz, Sniper, Slark, Phantom Assassin, Void Spirit, Storm Spirit, Ember Spirit, Earth Spirit, Spirit Breaker.
Undying
* 
Mirana can destroy Tombstone, and evade zombies using Leap and Moonlight Shadow's invisibility.
Io
* Heroes that can easily bypass Io's allies to get to Io: Riki, Tusk, Clinkz, Sniper, Slark, Phantom Assassin, Void Spirit, Storm Spirit, Ember Spirit, Earth Spirit, Spirit Breaker.
Io
* Heroes with both illusions and summons, for Io has nothing to deal with multiple enemies at once outside from Spirits's weak area-of-effect: Beastmaster, Broodmother, Chaos Knight, Lycan, Naga Siren, Nature's Prophet, Phantom Lancer, Shadow Shaman, Terrorblade, Visage, Warlock, Wraith King.
Io
* Heroes with either magical, physical or pure damage burst: Bane, Ember Spirit, Leshrac, Lina, Luna, Nyx Assassin, Phantom Assassin, Skywrath Mage, Tinker, Ursa, Void Spirit.
Undying
* Heroes with summons that are destroyed by a fixed number of attacks: Undying's Tombstone, 
Gyrocopter's 
Homing Missile, and 
Zeus's 
Nimbus.
Undying
* 
Reactive Armor makes Timbersaw very effective against heroes that control a lot of units, such as Broodmother, Lycan and Undying.
Undying
* Anti-Tank heroes like: 
Razor, 
Necrophos, Undying.
Io
* Tether and Overcharge makes it much harder for Pudge to kill a target with 
Meat Hook, and Relocate can save the Io's ally while 
Dismember is being channeled.
Undying
* Heroes with a slow attack rate will find themselves struggling to take out Tombstone, like 
Doom.
Io
* Heroes with the ability to heal allies, or those with good defensive abilities: 
Chen, 
Dazzle, Io, 
Oracle, 
Omniknight, Witch Doctor, 
Winter Wyvern, 
Abaddon, etc.
Undying
* Decay, Soul Rip and Flesh Golem all deal magical damage which ignores Bulwark.
* Decay reduces Mars' natural strength and therefore his health pool, which is what he relies on to trade effectively in lane.
Io
* Drow Ranger's lack of escape abilities makes her an easy target for Relocate ganks.
Io
* Phoenix's limit AoE, damage-over-time abilities give Io plenty of time to save allies with Relocate.
Undying
* Spectre must chase for kills and relies on movement speed for mobility in fights, and has no way to counter the Tombstone zombies.
* The potency of Soul Rip can be increased from nearby illusions from Haunt.
* Decay will shut down Spectre during the laning phase by effectively cutting down her initial health pool.
Additional:
* Spectre must chase for kills and relies on movement speed for mobility in fights, and has no way to counter the Tombstone zombies.
* The potency of Soul Rip can be increased from nearby illusions, so Undying can use 
Haunt against Spectre.
* Early game Decay will make Spectre easy to shut down in lane.
Undying
* Undying can use Decay not only to reduce Sven's maximum health, but also to reduce the damage he can deal with his ultimate.
* Zombies spawned by Tombstone together with Flesh Golem slow Sven down significantly. Landing Sven's powerful but somewhat slow right-click on Tombstone would be a waste.
Undying
* Decay can be good against Centaur Warrunner, as reducing the health of Centaur can make 
Double Edge risky.
* His zombies do not proc 
Retaliate, as it only procs for regular attacks.
Io
* Heroes with both illusions and summons, for Io has nothing to deal with multiple enemies at once outside from Spirits's weak area-of-effect: Beastmaster, Broodmother, Chaos Knight, Lycan, Naga Siren, Nature's Prophet, Phantom Lancer, Shadow Shaman, Terrorblade, Visage, Warlock, Wraith King.
Undying
* Undying's Tombstone will cheerfully chew through treants, incidentally netting you some extra income during fights.
* The above interaction tends to ensure that skirmishes are heavily populated with units, thereby buffing Soul Rip
Io
* Io can use Relocate with an ally to gank Nature's Prophet whenever he tries to push.
Additional:
* Nature's Prophet is extremely easy to gank with Relocate while he's split pushing.
* Tether on a friendly unit can destroy Nature Prophet's trees should he surround himself with 
Sprout as a defense.
Undying
* Generally, any fragile heroes will have a hard time dealing with Undying's tankiness, and even more so if Decay is used on them. Some examples are Crystal Maiden and Witch Doctor.
Io
* 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.
Undying
* Generally, any fragile heroes will have a hard time dealing with Undying's tankiness, and even more so if Decay is used on them. Some examples are Crystal Maiden and Witch Doctor.
Undying
* In general, melee heroes without blink mechanisms or spell immunity will have a hard time positioning against Pit of Malice: 
Sven, Tiny, Wraith King, 
Dragon Knight, 
Meepo, Doom, 
Bounty Hunter, 
Dark Seer, Undying, 
Alchemist, 
Legion Commander.
Io
* Io can escape from Pit of Malice with Tether or Relocate.
* Relocate can counter Dark Rift's split pushing.
Undying
* Meepo can quickly destroy Tombstone thanks to 
Divided We Stand.
Io
* Tether helps Io escape from Earthbind even if Meepo has Blink Dagger.
* Io's Spirits can pressure Meepo while laning and will usually hit at least one of his clones.
Io
* 
Quill Spray is very effective against Io, as it has very low armor and has to stay close to the fight to not break its Tether.
Undying
* Undying's Decay is a dangerous ability against Bristleback, as it makes him more vulnerable and reduces his tankiness.
* Undying's Tombstone together with Flesh Golem can slow Bristleback down significantly.
Io
* 
Cold Embrace can render the extra attack speed from Overcharge meaningless.
* 
Splinter Blast and 
Winter's Curse are very affective against Io, as it has to stay close to its tethered hero.
Undying
* Winter Wyvern cannot handle the Zombies created by Undying's Tombstone very well. In most situations, Zombies will have more movement speed than her.
* Undying can gain one or two easy Decay stacks on an ally in Cold Embrace. The ally will still take the damage as well.
Additional:
* Winter Wyvern cannot handle the Zombies created by Tombstone very well. In most situations, Zombies will have more movement speed than her.
* Undying can gain one or two easy Decay stacks on an ally in Cold Embrace. The ally will still take the damage as well, since it is magical.
Io
* Fireblast is a good tool to interrupt Io during its escapes through Tether.
* Ignite can be one of the few spells with enough total damage to out-trade the sustained healing Io provides for its fellow laner.
* However, picking other supports that focus less on the laning phase is generally a better choice against Io.
Undying
* Undying saps strength from heroes with Decay, and Ogre Magi's high strength gain will allow Undying to steal more and more strength, becoming stronger with each use.
* Due to the Strength steal from Decay, Undying is normally very tanky, and has high health, making it harder for Ogre Magi to kill him.
Io
* 
Duel is very effective against Io due to its low health and armor.
Io
* Tethered heroes are much harder for Legion Commander to kill in Duels.
* Relocate can cancel Duels and save allies.
Io
* 
Charge of Darkness can be used to escape or counter-initiate against a Relocate gank.
* 
Greater Bash and 
Nether Strike is devastating due to Io's low armor, and can even knock it away from tethered target.
Undying
* Due to Spirit Breaker's low attack speed, Tombstone is problematic for Spirit Breaker as the zombies summoned from Tombstone apply a stacking movement speed slow, which can significantly reduce Greater Bash's damage.
* Soul Rip and Decay allows Undying and his allies to survive from incoming ganks of Spirit Breaker.
Undying
* Luna's
Moon Glaives and 
Lunar Blessing can help her destroy Tombstone easily, and this becomes more effective if Luna is equipped with 
Manta Style.
Eclipse will strike only Undying, which can turn Undying's own ability against him.
Blade Mail which can turn Luna's burst damage against her, Luna often builds 
Black King Bar which will allow her to attack Undying freely because 
Blade Mail cannot pierce spell immunity.
Moon Glaives and 
Lunar Blessing can help her destroy Tombstone easily, and this becomes more effective if Luna is equipped with 
Manta Style.
Eclipse will strike only Undying, which can turn Undying's own ability against him.
Blade Mail which can turn Luna's burst damage against her, Luna often builds 
Black King Bar which will allow her to attack Undying freely because 
Blade Mail cannot pierce spell immunity.
* Spell Immunity of Zombies from Tombstone is a total disadvantage against Luna because
* Though Undying often builds
Additional:
* Luna's
* Spell Immunity of Zombies from Tombstone is a total disadvantage against Luna because
* Though Undying often builds
Io
*
Lucent Beam and 0.25s Eclipse Lucent Ministun talent for 
Eclipse can be used to cancel both, Tether and Relocate.
Moon Glaives and 
Eclipse abilities can make short work of Io and its tethered ally, particularly when upgraded with 
Aghanim's Scepter.
Lucent Beam can be used to cancel both, Tether and Relocate.
Diabolic Edict, 
Lightning Storm and 
Pulse Nova abilities. Luna's 
Moon Glaives and 
Eclipse abilities can make short work of Io and its tethered ally, particularly when upgraded with 
Aghanim's Scepter.
* Luna's
Additional:
*
* Like with Leshrac's