Io

Io the Guardian Wisp is a ranged strength hero who works best as part of a communicative team. With its support-oriented skill set, Io is able to share its strength through Tether and Overcharge, harass enemy heroes out of the lane with Spirits, and materialize itself and an ally anywhere on the map with Relocate. Gank enemy heroes, push undefended lanes, save teammates from deep within enemy territory—the possibilities are endless, and Io features one of the highest skill ceilings in the game.

Io, unlike other heroes, does not need to be facing towards a unit in order to attack, use abilities, or items. It still has a front, marked by an arc-like effect, and a back.

Recommended items
Starting:
 * give Io a bit of extra health and damage. They can be used to build into an.
 * es, s, and potions can be used to sustain Io and a lane partner, thanks to Tether.

Early-game:
 * give a nice movement speed boost.
 * restores mana and health in a pinch to both Io and a tethered ally.
 * can be used in conjunction with Tether to restore a large amount of health to Io and an ally.

Core:
 * is a cheap upgrade from . It helps Io heal allies even more.
 * Io can use to heal a tethered partner for 625 health, as opposed to the standard 250.
 * can be used to restore a large amount of mana to Io and his allies, thanks to Tether.

Situational:
 * makes Io a very effective healer, thanks to its powerful health regeneration.
 * provides a useful aura that can help in ganks and the slow can allow less mobile allied heroes to get closer to their targets.
 * provides a valuable disable, and also some useful attribute bonuses.
 * gives some strength and evasion, and the ability to disarm an enemy hero that is causing trouble to your team.
 * can be used during Relocate to aid in a gank or push.
 * gives you cost efficient attribute bonuses and further boosts you and your tethered partner's attack and movement speed.
 * provides extra burst damage that you might need to take down an enemy hero in a Relocate gank.
 * is the next logical step for an Io with Mekansm and Arcane Boots, as it combines the two items into one slot, potentially allowing another item in your inventory.

Tips

 * can be used on allied heroes to get to their side with great speed, as it latches from a considerable distance.
 * Approaching a confrontation from behind will allow for easier use of Tether's slow. Positional items are also useful for this.
 * requires much practice and focus to control, and due to its high mana cost it is not advisable to use it frivolously.
 * Building or other health regen items will allow for much more liberal use of your Overcharge. Also, the regen you get from these items will heal your tethered partner, allowing you to heal allies by using Overcharge.
 * The same can be said with building a but regenerates mana instead of health which is useful to heroes with frequent mana problems. It can also be used in conjunction with other supports with healing abilities such as 's
 * Remember that can be used on friendly creeps and summons, and in a dangerous situation Io may be able to avoid death by tethering to a lane creep, owing to Tether's large latch distance.
 * Should an emergency arise, Io may Tether to a wounded ally and then Relocate to the fountain to heal both Io and his ally.
 * You can also save the life of a crucial allied hero with this method, but it will often result in your own inevitable death when Relocate forces you to return to your original location. Be sure to break the Tether to your ally before you return.
 * The inverse of this can also work; Relocate from your fountain to the crucial ally and Tether them to bring them back. This is not always viable however, as it entails the 12 second discrepancy between Relocations.
 * If Io's team has an end-game carry such as or, his top priority becomes ensuring the survival of this hero at any cost, including his own life. Io's skillset makes him very good at doing this, and if Io succeeds in preserving the life of their carry, they will eventually become hugely powerful, and most likely win the game for their team.
 * A good way to make Io cause a lot of damage with his nuke quickly is to summon the Spirits, make them get closer, and when the cooldown has ended, get close to the enemy and activate the spell again. This way, all the spirits around you will explode damaging the enemy and five new ones will appear, potentially exploding on him too. This is used best when Io is laning with someone with a good slow or stun, and when used to maximum potential (exploding all 10 spirits at maximum level) can deal an enormous burst of magical damage.
 * When ganking or escaping, always remember that Tether duration is the same as its cooldown, so it can be maintained on constantly as long as you have enough mana.
 * Though using Tether to offer bonus healing from items such as or an  charge is a good idea, your Tethered ally will not gain anything if you are at full health. Using Overcharge to lower your health before using any healing items will assure you are able to pass along the boosted regeneration.
 * However, for mana, it does not matter if Io is full or not. Mana will always be transfered, regardless of Io's mana status.
 * is an excellent Item if you have Tranquil Boots so that you can give your Tethered target health regen and also the mana from using the active of Soul Ring.
 * A is good for the same reasons as Soul Ring; healing yourself and your partner in battle, and as well as giving mana.
 * ,, and (with ) synergise well with Io; while not good heroes for Io to attach himself to (see below), all offer map control which combines well with Relocate. Not to mention the demoralizing effect of Relocating a Techies in range to.
 * Although highly irregular, a skilled player could greatly benefit from an . The passive health regeneration synergizes well with Tether and the bonus armor combined with proper armlet toggling can allow Io to survive several situations they otherwise wouldn't. The health drain from Unholy Strength can also be used to lower one's health without draining their mana as overcharge would. However, an Armlet should only be considered if someone on Io's team has already purchased a or if other conventional items would be less useful.
 * Invisible enemy heroes cause the Spirits to collide and sustain damage, but their invisibility will remain. This can help determine the location of nearby invisible enemy heroes such as 's Cloak and Dagger as the collision is audible and location known.

Io Partners
The most common playstyle for Io is to be partnered with a Carry, preferably one with mobility or health regen issues (as Io can help make up for both). Although any durability-focused carry can benefit from Io's support, among the better known Io Buddies are:


 * , whose mobility issues are almost negated by the proper use of Relocate. In addition, ing Io to an enemy while tethered will guarantee a slow, while his attack speed increase immensely helps Tiny's biggest issue, which is his very slow attack speed. Finally, his mana regeneration allows to become an extraordinary ganking force very early as Tiny's miniscule mana pool limits his presence early on. When playing with a Tiny, it is incredibly valuable to purchase a, since it increases Tiny's poor armor, scales very well with his base damage, and allows him to Lifesteal in fights.
 * , due to allowing Relocate to take three heroes, including Io (four with Aghanim's Scepter on Lifestealer) instead of two. ('s  is similarly useful.)
 * , whose can bring an enemy into the Tether slow.
 * , who benefits greatly by the mobility granted by Io.
 * , due to his ability to blink behind targets to trigger Tether slow while in . The attack speed bonus from Overcharge synergizes extremely well with.
 * , like Riki and Chaos Knight, can use her Phantom Strike to trigger Tether's slow. Overcharge also synergizes very well with her, making her more durable and allowing her to get more hits in.
 * , who has a terrifying presence with Relocate and can deal large amounts of damage in a short amount of time under the benefits of Overcharge.
 * immensely benefits from every feature that Io grants him; High mobility and mana regeneration to continuously cast and avoid kiting, higher attack speed to take advantage of Sven's intense damage (Particularly under, and higher survivability to go along with Sven's natural tankiness and appease his necessity to consistently be on the frontlines and thus be focused, granting him more time to do damage. Additionally, his stun is an AoE, meaning the player could stun AND slow multiple units at once with a well place stun.
 * 's heal is very powerful when combined with Tether. Io's Relocate can be used to pick off lone enemies using . Overcharge will increase the damage done during Duel and also reduce the damage taken during it. In addition, its very easy to hit all Spirits/Tether slow when the target is stuck in a duel.
 * is paired with Io commonly in mid lane to make Morphling's life easier and allowing him to nuke down his opposition quickly and efficiently. The second way that Io is utilised with Morphling is by giving him a another escape on top of and switching to his ; Io also gives him incredible attack speed and even more durability. Furthermore, Relocate allows the Morphling to have a greater global presence and allows him to split-push with increased safety.
 * is a nice partner that synergises well with Io since Io's Relocate allows you to gank opponents and nuke them down with, and . Furthermore, it gives Gyrocopter durability in the early and mid game which he lacks without an Io.
 * is a very nice partner for Io due to causing Io to heal Juggernaut for an extra 1.5 times the amount Io is being healed due to Tether. Also, 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.
 * , whose becomes more powerful with higher movement speed, and benefits from the attack speed increase greatly. His mobility also removes the necessity for the two to be on the same place to setup a gank, as Spirit Breaker can simply select a target with  across any point of the battlefield, while Io can Relocate himself to the position.

Keep in mind that any heroes who can manipulate position such as would be a strong counter for this type of strategy

Trivia

 * Io is the name of a priestess of Hera in Greek Mythology. She was seduced by Zeus and subsequently incurred Hera's wrath.
 * Io is also the name of one of four Galilean moons of Jupiter, which was named after the same character in Greek Mythology.
 * Io's fun names in DotA were Weird Ball and Santelmo. Santelmo may refer to St. Elmo's Fire, a weather phenomenon that creates sparks of bright energy similar to that of lightning, mostly occurring from sharply pointed structures.
 * ,, , and together represent the four fundamental forces of the universe with Io representing the electromagnetic force, as alluded to in his lore as the force that binds all matter together, as well as his abilities which mostly rely on being bound to a partner to achieve maximum effect.