Io/Counters

Bad against...

 * During a gank, Bloodseeker will often kill Io first and steal its health.


 * Bristleback is almost impossible to take down with a Relocate gank.


 * With, Clinkz will nearly always kill Io, even if he Tethers away.


 * will often counter.


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


 * Io has fewer Strength armor and HP base, so LC can get victory point without tired.


 * His Bear can reach and cause him some problems.


 * will easily reach.


 * 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.


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

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.