Dark Seer
* Heroes with fast movement abilities will suffer huge damage when afflicted by Rupture: 
Spirit Breaker, 
Earth Spirit, 
Dark Seer.
Additional:
* 
Rupture can deal a lot of damage to either a surged Dark Seer or his allies and prevent the target from getting into position.
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.
Dark Seer
* 
Flame Guard makes Dark Seer not deal any damage with his skills to Ember 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.
Dark Seer
* A Sniper who is somewhat competent at positioning is hardly going to be affected by any of Dark Seer's spells thanks to 
Take Aim.
* However, an illusion of Sniper made with Wall of Replica is extremely powerful, and hard to deal with.
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.
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 his 
Tethered target.
Dark Seer
* 
Fortune's End dispels Ion Shell and Surge, making any gank attempt on Dark Seer in the laning phase likely to succeed.
* 
Fate's Edict prevents all magical damage that comes from Dark Seer's abilities.
* Fortune's End dispels Ion Shell on creeps, which Dark Seer relies on to farm and zone.
Additional:
* Fortune's End can dispel 
Ion Shell, a skill that helps Dark Seer immensely in the laning phase, as well as 
Surge, a move-speed buff, effectively allowing Oracle to control Dark Seer, especially in the laning phase.
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.
Io
* 
Poison Touch allows Dazzle to harass both, Io and it's tethered target on lane. 
Aghanim's Shard upgraded Poison Touch can also hex both, Io and it's tethered target, preventing them from escaping with Relocate, and also disarming them, silencing them, muting them and rendering them helpless against Dazzle and his allies.
* Io's damage output is one of the weakest, therefore Dazzle will have plenty of time to save an ally with 
Shallow Grave from gank by Io and it's tethered target.
* 
Shadow Wave will always hit both, Io and it's tethered target if they are near the ally Dazzle uses Shadow Wave on, while healing Dazzle's allies near them. Aghanim's Scepter upgraded Shadow Wave can bounce on both, Io and it's tethered target, causing them both to take damage and to be attacked by Dazzle. And unlike Io who doesn't get healed while using Tether, Shadow Wave will always heal Dazzle no matter on which of his allies he uses it on.
* 
Bad Juju will cause both, Io and it's tethered target to lose armor every time Dazzle casts a spell while strengthening armor of Dazzle's allies.
Additional:
* Poison Touch allows Dazzle to harass both, Io and it's Tethered target on lane. Aghanim's Shard upgraded Poison Touch can also hex both, Io and it's Tethered target, preventing them from escaping with Relocate, and also disarming them, silencing them, muting them and rendering them helpless against Dazzle and his allies.
* Io's damage output is one of the weakest, therefore Dazzle will have plenty of time to save an ally with Shallow Grave from gank by Io and it's Tethered target.
* Shadow Wave will always hit both, Io and it's Tethered target if they are near the ally Dazzle uses Shadow Wave on, while healing Dazzle's allies near them. Aghanim's Scepter upgraded Shadow Wave allows Dazzle Shadow Wave directly on Io and it's Tethered target which can also bounce on both, Io and it's tethered target, causing them both to take damage and to be attacked by Dazzle. And unlike Io who doesn't get healed while using Tether, Shadow Wave will always heal Dazzle no matter on which of his allies he uses it on.
* Bad Juju will cause both, Io and it's tethered target to lose armor every time Dazzle casts a spell while strengthening armor of Dazzle's allies.
Io
* 
Strafe, 
Tar Bomb and 
Burning Barrage from Aghanim's Shard 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
* 
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.
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 his Tethered target.
Io
* 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.
Additional:
* 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.
Dark Seer
* Dark Seer's strength lies in his high-mana cost skills. So 
Mana Break can be a great nuisance for him, since it can reduce his mana and prevent him from casting his spells.
* 
Mana Void can deal a lot of damage if Dark Seer spent a lot of mana on his abilities.
Dark Seer
* 
X Marks the Spot prevents Dark Seer or his allies from escaping with Surge.
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.
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.
Io
* 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.
Additional:
* Grimstroke can catch Io and his Tethered ally easily with 
Soulbind as Io has a tendency to Tether himself with an ally frequently, which also makes them easier targets for Soulbind.
* Io is highly vulnerable to disables. Hence, Grimstroke's 
Phantom's Embrace is a great ability to hinder Io's potential.
Dark Seer
* 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.
Io
* 
Homing Missile can be used to cancel escape attempts with Relocate.
* 
Flak Cannon allows Gyrocopter to attack both, Io and his Tethered target, especially when upgraded with Aghanim's Scepter.
* 
Rocket Barrage and 
Call Down allow Gyrocopter to deal serious damage to both Io and his Tethered target.
Additional:
* Homing Missile can be used to cancel escape attempts with Relocate.
* Flak Cannon allows Gyrocopter to attack both, Io and his Tethered target, especially when upgraded with Aghanim's Scepter.
* Rocket Barrage and Call Down allow Gyrocopter to deal serious damage to both Io and his Tethered target.
Dark Seer
* 
Spell Steal will easily steal all abilities from Dark Seer.
Additional:
* Spell Steal can perfect from Rubick's steal all abilities from Dark Seer. Rubick's always purchase Aghanim's Scepter can two stolens abilities from Dark Seer's and waiting for seconds for second stolen abilities (example: combinated Vacuum and Wall of Replica) and many different combination.
* A good positoning from Rubick's Spell Steal waiting steal abilities from Dark Seer 
Wall of Replica and illusion from Wall of Replica Dark Seer's can fighting with effect from outcome steal Wall of Replica from Rubick's.
* Combinated Rubick's steal Surge and 
Blink Dagger is very important catch from Dark Seer's and enemies.
* Rubick's 
Telekinesis can lifted up Dark Seer or enemy heroes and throw to Wall of Replica from Rubick's steal.
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
* 
Lucent Beam can be used to cancel both, Tether and Relocate.
* Like with Leshrac's 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.
Additional:
* Lucent Beam and 0.25s Eclipse Lucent Ministun talent for Eclipse can be used to cancel both, Tether and Relocate.
* Luna's Moon Glaives and Eclipse abilities can make short work of Io and its tethered ally, particularly when upgraded with Aghanim's Scepter.
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 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 whose abilities can affect multiple enemies at once: 
Dawnbreaker, Ember Spirit, Lina, Luna, 
Jakiro, Leshrac, 
Invoker, 
Muerta, 
Dazzle.
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 are hard to gank: 
Axe, 
Death Prophet, Phantom Lancer, 
Slark, 
Centaur Warrunner, 
Bristleback, 
Medusa, 
Mars.
Io
* Heroes that are hard to gank: Axe, Death Prophet, Phantom Lancer, Slark, Centaur Warrunner, Bristleback, Medusa, Mars.
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, Muerta, Dazzle.
Io
* Heroes that are hard to gank: Axe, Death Prophet, Phantom Lancer, Slark, Centaur Warrunner, Bristleback, Medusa, Mars.
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
* Squishy heroes (Io, Crystal Maiden, Lina...), as Earth Spirit can deal tons of damage with Magnetize.
Io
* Heroes that are hard to gank: Axe, Death Prophet, Phantom Lancer, Slark, Centaur Warrunner, Bristleback, Medusa, Mars.
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.
Dark Seer
* Dark Seer relies on Surge for most of his mobility, so he's not very vulnerable to slows, but much more to root effects and walls or pseudo-walls such as 
Disruptor's 
Kinetic Field or Slark's 
Pounce.
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, 
Lifestealer.
Dark Seer
* Heroes with AoE abilities will hit Slark in Shadow Dance: Lina, Jakiro, 
Underlord, Leshrac, Dark Seer, 
Earthshaker, 
Timbersaw, Crystal Maiden.
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.
Dark Seer
* Dark Seer's only disable is Vacuum. Though he starts off with high armor and health, he'll eventually have a hard time dealing with high mobility heroes such as 
Weaver or Queen of Pain.
Dark Seer
* Dark Seer's only disable is Vacuum. Though he starts off with high armor and health, he'll eventually have a hard time dealing with high mobility heroes such as Weaver or Queen of Pain.
Dark Seer
* In general, heroes who are melee with no way to fight back can be very easily poked by Monkey King to gain his Jingu Mastery stacks: Dark Seer, Riki, 
Rubick.
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, Lifestealer.
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, Lifestealer.
Dark Seer
* Strong laners are usually at a disadvantage because of how well Sven can jungle. Heroes such as Dark Seer. Underlord and 
Legion Commander may find that later Sven takes care of them very quickly after some jungle farming.
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, Lifestealer.
Io
* Heroes that are hard to gank: Axe, Death Prophet, Phantom Lancer, Slark, Centaur Warrunner, Bristleback, Medusa, Mars.
Io
* Heroes whose abilities can affect multiple enemies at once: Dawnbreaker, Ember Spirit, Lina, Luna, Jakiro, Leshrac, Invoker, Muerta, Dazzle.
Io
* Heroes with the ability to heal allies will not be able to heal heroes affected by 
Doom: 
Chen, Dazzle, Io, 
Oracle, 
Omniknight, Witch Doctor, 
Winter Wyvern, 
Abaddon, etc.
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
* 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.
Dark Seer
* The haste provided by Dark Seer's Surge or a {Rune:Haste} renders Lich's slows ineffective.
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 with Tether or Relocate.
* 
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.
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.
* 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.
Dark Seer
* Heroes that rely on illusions typically spawn very strong illusions inside Dark Seer Wall of Replica that he can use against them or their team: Phantom Lancer, Chaos Knight, Naga Siren, Terrorblade.
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.
Dark Seer
* With 
Normal Punch from Aghanim's Scepter, Dark Seer can gain an advantage against heroes who rely on evasion as Normal Punch has true strike: Phantom Assassin, 
Windranger, 
Hoodwink.
Dark Seer
* Dark Seer can take great advantage of 
Divided We Stand by putting an Ion Shell on a clone in order to harass them effectively.
* Vacuum can take a single Meepo and disable him for Dark Seer and his teammates to take out.
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.
Dark Seer
* Dark Seer's 
Vacuum and Ion Shell can clear a wave of Chen's Creeps effectively.
* Surge applies haste movement and negates the slow from 
Penitence, allowing Dark Seer to easily escape from Chen and his creeps.
* Dark Seer's full combo from Dark Seer's Vacuum, Wall of Replica and Normal Punch from Aghanim's Scepter can often kill Chen or any of his allies before he can save them with 
Hand of God.
Additional:
* Dark Seer's Vacuum and Ion Shell can clear a wave of Chen's Creeps effectively.
* Surge applies haste movement and negates the slow from Penitence, allowing Dark Seer to easily escape from Chen and his creeps.
* Dark Seer's full combo from Dark Seer's Vacuum, Wall of Replica and Normal Punch from Aghanim's Scepter can often kill Chen or any of his allies before he can save them with Hand of God.
Dark Seer
* 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.
Dark Seer
* 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.
Io
* Io can escape from Pit of Malice with Tether or Relocate.
* Relocate can counter Dark Rift's split pushing.
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.
Dark Seer
* Heroes that rely on summons will suffer against Ion Shell, which kills them very quickly: Beastmaster, Broodmother, Enigma, Nature's Prophet, Visage, Warlock, Wraith King.
Io
* 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.
Dark Seer
* 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.
Io
* Drow Ranger's lack of escape abilities makes her an easy target for Relocate ganks.
Dark Seer
* Ion Shell destroys 
Refraction's protection stacks in short time.
* Surge ignores the massive slow from 
Psionic Trap.
Io
* Phoenix's limit AoE, damage-over-time abilities give Io plenty of time to save allies with Relocate.
Dark Seer
* Heroes with haste can negate Enchant's slow: Weaver, Dark Seer, Lycan, Centaur Warrunner.
Dark Seer
* Heroes who do not have nor rely on passive abilities make Nethertoxin much less effective: Clinkz, Pugna, Nature's Prophet, Dark Seer, Lycan, Tusk
Dark Seer
* Certain heroes can mess up with Pangolier's positioning and timing (especially if he intends to use Rolling Thunder during combat): 
Vengeful Spirit, 
Keeper of the Light, 
Huskar, Dark Seer
Dark Seer
* With Normal Punch from Aghanim's Scepter, Dark Seer can gain an advantage against heroes who rely on evasion as Normal Punch has true strike: Phantom Assassin, Windranger, Hoodwink.
Dark Seer
* Dark Seer can increase the movement speed of allies with Surge, breaking Static Link.
Dark Seer
* With Normal Punch from Aghanim's Scepter, Dark Seer can gain an advantage against heroes who rely on evasion as Normal Punch has true strike: Phantom Assassin, Windranger, Hoodwink.
Dark Seer
* Heroes with hastes: Dark Seer, Lycan
Dark Seer
* Heroes that rely on summons will suffer against Ion Shell, which kills them very quickly: Beastmaster, Broodmother, Enigma, Nature's Prophet, Visage, Warlock, Wraith King.
Dark Seer
* Dark Seer can pull together Spectre's illusions with Vacuum, and Wall of Replica creates an illusion of Spectre that deals massive damage.
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.
Dark Seer
* Abilities that deal low damage with high amounts of instances are irrelevant against Pudge during Flesh Heap's active: Gyrocopter's Rocket Barrage and Dark Seer's Ion Shell are just a couple examples.
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.
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.
Dark Seer
* Ion Shell zones out Broodmother in the laning phase, and can kill her spiderlings if used on one Spiderling in a group.
* Vacuum can pull Broodmother out of the treeline.
Additional:
* Ion Shell is a very powerful weapon against Broodmother's Spiderlings and makes her laning much harder.
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.
Dark Seer
* Heroes that rely on illusions typically spawn very strong illusions inside Dark Seer Wall of Replica that he can use against them or their team: Phantom Lancer, Chaos Knight, Naga Siren, Terrorblade.
Additional:
* Ion Shell helps taking down illusions quickly, making it easy to identify the real Phantom Lancer.
* Surge allows Dark Seer and his teammates to run away from Phantom Lancer, who relies on his 
Phantom Rush to chase enemies.
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.
Dark Seer
* Heroes that rely on summons will suffer against Ion Shell, which kills them very quickly: Beastmaster, Broodmother, Enigma, Nature's Prophet, Visage, Warlock, Wraith King.
Io
* 
Living Armor and 
Leech Seed can be used to save a hero from a Relocate gank.
* 
Overgrowth can be used to cancel escape attempts with Relocate.
* Once Treant Protector buys Aghanim's Scepter, he will gain access to 
Eyes in the Forest, that will allow him to enchant a tree which will grant him unobstructed vision in that location, allowing him to keep his allies alerted on Io and his Tethered's attempts to gank them, and which can also allow Overgrowth to damage them and root them if they are within a 800 radius of an tree affected by Eyes in the Forest.
Dark Seer
* Living Armor can be destroyed quickly with Ion Shell.
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.
Dark Seer
* Heroes that rely on illusions typically spawn very strong illusions inside Dark Seer Wall of Replica that he can use against them or their team: Phantom Lancer, Chaos Knight, Naga Siren, Terrorblade.
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 his 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.
Dark Seer
* Dark Seer's Vacuum and Ion Shell allows him to clear a wave of Terrorblade's illusions.
* Because Terrorblade often builds items that require 
Ultimate Orb like Manta Style and 
Eye of Skadi, Dark Seer can create a very strong illusion of Terrorblade with Wall of Replica and Normal Punch from Aghanim's Scepter.
* If Dark Seer can use Vacuum to help teammates land their AoE abilities, Terrorblade will be quickly killed before he even gets a chance to use Sunder.
Additional:
* Dark Seer's Vacuum and Ion Shell allows him to clear a wave of Terrorblade's illusions.
* Because Terrorblade often builds items that require Ultimate Orb like Manta Style and Eye of Skadi, Dark Seer can create a very strong illusion of Terrorblade with Wall of Replica and Normal Punch from Aghanim's Scepter.
* If Dark Seer can use Vacuum to help teammates land their AoE abilities, Terrorblade will be quickly killed before he even gets a chance to use Sunder.
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.
Dark Seer
* Heroes that rely on summons will suffer against Ion Shell, which kills them very quickly: Beastmaster, Broodmother, Enigma, Nature's Prophet, Visage, Warlock, Wraith King.
Additional:
* Surge allows for Dark Seer and his allies to escape from Upheaval due to it ignoring any slow.
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
* 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.
Dark Seer
* 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.
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, Lifestealer.
Dark Seer
* Heroes with escape abilities: Anti-Mage Dark Seer Slark Storm Spirit Windranger Weaver can kite Lifestealer due to him having no lockdown.
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.
Dark Seer
* Heroes that rely on summons will suffer against Ion Shell, which kills them very quickly: Beastmaster, Broodmother, Enigma, Nature's Prophet, 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.
Dark Seer
* Heroes that rely on summons will suffer against Ion Shell, which kills them very quickly: Beastmaster, Broodmother, Enigma, Nature's Prophet, Visage, Warlock, Wraith King.
Dark Seer
* Dark Seer relies on Surge for most of his mobility, so he's not very vulnerable to slows, but much more to root effects and walls or pseudo-walls such as
Disruptor's 
Kinetic Field or 
Slark's 
Pounce.
Io
* Disruptor can always Glimpse back Io or his target after he
Relocated nearby.
Tethered away in the fog of war.
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.
* 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
Additional:
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