Io/Counters

Bad against...

 * Ancient Apparition's prevents any healing of Io and can even make a succesfull  rescue to the team's fountain useless.


 * If either Io or his ed target is at low health during, Bloodseeker will always see where they end up thanks to.
 * Because Io needs to always stay near the ed target to make use of, Bloodseeker can Io so that Io is forced to stay in place, which means either the Tethered target will have to break the tether, or will have to stay near Io for Rupture's duration.


 * Bristleback is difficult to take down with a gank.
 * Because Io needs to stay close to his ed target, he is likely to be hit by . Io has very bad armor, so Quill Spray is very good against Io.


 * Because of Io's low armor and health, a combination of and  will be the swift end of Io.


 * will often counter.


 * Legion Commander can easily kill Io during the duration of due to Io's low strength and armor.


 * will usually hit both Io and his ed target since both will be close enough for the lightning to jump. It can then be followed up by.
 * and hit all units near Leshrac, meaning he can do colossal damage to Io and his ed target.


 * His Bear can reach and cause him some problems.


 * will easily reach.
 * illusion will soak up the damage done from so that the Spirits don't explode on any of Phantom Lancer's allies.


 * can be used to counter-initiate against any gank.
 * and is devastating due to 's low armor, and can even knock him away from his ed target.


 * often saves a hero from Io's team gank.


 * Can effectively counter Relocate ganks, as well as solo kill Io and its buddy if there are no other units nearby to split the Cask stuns.


 * can render the extra attack speed from meaningless.
 * Because Io likes to keep close to his hardest carry with, he is an easy and perfect target for and.

Others

 * In general, heroes that are resistant to ganking will do well against Io.
 * Heroes that can easily get Io, passing through his allies (such as, , , ), will do really well against him, as Io is a priority target due to great supporting abilities and relatively squish ( also takes a good amount of health from Io).

Items

 * 's base armor is extremely low, and causes him to struggle against armor-reducing items.
 * 's damage output is low. Magic resistance items will diminish it even more.
 * will do well against due to his frailty, disrupting his positioning.
 * shuts down 's mobility.

Good against...

 * Nature's Prophet is extremely easy to gank with Relocate while he's split pushing.


 * Because Io always aimed first, he may build Blade Mail for March of the Machines.
 * Farmed well Io can kill Tinker or assist for Tinker's death.


 * Io's Tether can escape from Earthbind even Meepo has Blink Dagger.
 * Io's Spirits can pressure Meepo while laning and chase the weakest Meepo.


 * Io can escape from Pit of Malice with Tether or Relocate.
 * Io relocate can counter Dark Rift push. Especially if his teammate is Lifestealer or any hero with Boots of Travel 2.


 * She doesn't have much mechanisms to reach, so she will have do deal with his buffed ally.
 * She is quite vulnerable to ganks, shutting her down in the early stages before she can have more impact than a simple bestower.

Others

 * Keep in mind, can't do anything alone. He is one tough Hero to play, heavily depending on the bonds between players.
 * If these are good, excels against Heroes lacking escapes as he Relocates his ally in order to ambush the enemy..

Works well with...

 * can bring an enemy into the Tether slow.
 * can stun the enemy long enough to finish them.


 * causes Io to heal Juggernaut for an extra 1.5 times the amount Io is being healed due to Tether.
 * When Juggernaut uses, Io's Tether will persist, allowing for an easy team wide slow due to Juggernaut jumping between the enemy team. This is especially effective if Juggernaut has.


 * 's heal is very powerful when combined with Tether.
 * 's can be used to pick off lone enemies using.
 * 's will increase the damage done during Duel and also reduce the damage taken during it.


 * With, Io can Relocate two heroes at the same time (three if Lifestealer has ).


 * 's jump will usually trigger Tether's slow.
 * makes Phantom Assassin more durable and allows her to get more hits in.


 * becomes more powerful with higher movement speed, and benefits from 's attack speed increase greatly.


 * Sven's mobility is greatly improved by Tether.
 * and will take down an enemy in no time.
 * Mana regeneration from Io's items benefits Sven greatly.


 * Tiny's burst damage with and  is ideal for finishing off enemies quickly.
 * Tiny can also Io if the enemy gets away.
 * partly solves any health regen issues Tiny has.
 * helps negate Tiny's mobility issues.
 * really helps with Tiny's attack speed issues.


 * Ursa's mobility is greatly improved by Tether.
 * will allow Ursa to dish out heavy damage with.

Others

 * In general, heroes that can stun and beat down an opponent quickly will work well with Io.
 * Heroes that provide vision help Io pick ideal places to Relocate:, ,.
 * It is possible to Relocate Techies in range for.
 * AoE healing spells, combined with, can provide 250% amount of regeneration to the tethered target. Heroes with such spells like , , and , can make a perfect support duo with.

List of heroes that counter Io, and list of heroes that work well with Io.