Io the Guardian Wisp is a singular 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 to attack, use abilities, or items. It still has a front, marked by an arc-like effect, and a back.
- Io has no equipments currently.
- Tether 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.
- Spirits requires much practice and focus to control, and due to its high mana cost it is not advisable to use it frivolously.
- Building Heart of Tarrasque 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.
- Remember that Tether 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 Phantom Assassin or Faceless Void, 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 he succeeds in preserving the life of his 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 Tranquil Boots or an Urn of Shadows 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.
- Soul Ring 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 Bottle is good for the same reasons as Soul Ring; healing yourself and your partner in battle, and as well as giving mana.
- Techies, Templar Assassin, and Treant Protector (with Eyes in the Forest) 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 Suicide Squad, Attack!.
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:
- Tiny, whose mobility issues are almost negated by the proper use of #RelocateRelocate. In addition, Tossing Io to an enemy while tethered will guarantee a slow.
- Lifestealer, due to Infest allowing Relocate to take three heroes (including Io) instead of two. ( Nature's Prophet's Teleportation is similarly useful.)
- Chaos Knight, whose Reality Rift can bring an enemy into the Tether slow.
- Ursa, who benefits greatly by the mobility granted by Io.
- Riki, due to his ability to blink behind targets to trigger Tether slow while in Smoke Screen. The attack speed bonus from Overcharge synergizes extremely well with Backstab.
- Phantom Assassin, like Riki and Chaos Knight, can use her Phantom Strike|blink to trigger Tether's slow. Overcharge also synergizes very well with her, making her more durable and allowing her to get more hits in.
- Slardar and Sven, both who have a terrifying presence with Relocate and can deal large amounts of damage in a short amount of time under the benefits of Overcharge.
- Legion Commander's heal is very powerful when combined with Tether. Io's Relocate can be used to pick off lone enemies using Duel. 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.
- Morphling 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 Waveform and switching to his Replicate; 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.
- Gyrocopter is a nice partner that synergises well with Io since Io's Relocate allows you to gank opponents and nuke them down with Rocket Barrage, Flak Cannon and Call Down. Furthermore, it gives Gyrocopter durability in the early and mid game which he lacks without an Io.
- Juggernaut is a very nice partner for Io due to Healing Ward causing Io to heal Juggernaut for an extra 1.5 times the amount Io is being healed due to Tether. Also, when Juggernaut uses Omnislash, 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 Aghanim's Scepter.
- 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.
- Wisp is the name of an Elemental from the Legend of Mana series, which has a similar appearance and is usually involved in healing.
- 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 occuring from sharply pointed structures.
- Enigma, Io, Keeper of the Light, and Chaos Knight 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.
- Fixed the mechanism Armlet of Mordiggian and Overcharge to use proper health modification (meaning their health manipulation is now completely unaffected by anything).
- Fixed Tether sharing mana regeneration when you have full mana.
- Fixed Spirits initially spawning 250 units away instead of 150 units.
- Fixed Relocate not being interrupted if Io was only disabled in the cast time but not when the teleportation happened.
- Fixed Relocate not getting interrupted by Root debuffs ( Ensnare, Overgrowth, etc).
- Fixed Relocate not revealing Fog of War for enemies.
- Fixed Relocate not showing the initial visual effect on the ground for enemies (only showed ping).
- Fixed being able to return creeps with Relocate by Tethering a creep after relocating.
- Fixed Overcharge missing a 2 second toggle cooldown.
- Fixed Tether sometimes ending prematurely if Relocate was cast before Tether.
- Fixed Relocated units sometimes walking away to do a previous order.
- Updated the textures for Death Prophet, Silencer, Drow Ranger, and Io.
- Updated the ability icons for Death Prophet, Silencer, and Io to match texture changes.
- Enabled Rubick, Io, and Luna in Captain's Mode.
- Fixed Magic Stick interaction with Tether.
- Overcharge and the two Spirits control sub abilities no longer proc Magic Stick.
- Spirits no longer don't retain their vision after they explode.
- Fixed Relocate's return not interrupting other channeling spells (like Town Portal Scroll).
- Fixed heroes continuing old movement orders after returning with Relocate.
- Fixed Soul Ring not working with Tether.
- Fixes for Io's rendering with pops and such when entering/leaving FoW.
- Fixed Io voice lipsync getting stuck on with random noise.
- Fixed ranged display stomping on ambient effects, including Io.
- Fixed Tether being left behind when enemy teleported into FoW.
- Changed Io Explosion Effects.
- Added more obvious Tether boundary effect.
- Tether now shows the amount that it heals its target.
- Spirits no longer show up on the minimap.
- Io and his tethered unit move their camera when they Relocate and Relocate back.
- The Relocate sound stops correctly now.
- Added Luna, Io.
- No longer requires turning to perform any actions.
- Spirits no longer provide vision, except temporarily when they collide with an enemy hero.
- Increased Overcharge health/mana cost over time from 3.5% to 4.5%.
- Increased Overcharge health/mana cost over time from 2.5% to 3.5%.
- Tether regeneration transfer now heals the Tethered unit at 1.5x the rate of Io.
- Added to Captain's Mode.
- Increased Base attack damage increased from 16-25 to 26-35 (total damage is now 43-52).
- Increased Attack range from 525 to 575.
- Reduced attack speed bonus from 60/80/100/120 to 40/50/60/70.
- now also grants 5%/10%/15%/20% incoming damage reduction towards all damage types.
- This effect also transfers to the tethered ally.Reworked:
- Reduced Tether movement speed bonus from 20%/25%/30%/35% to 15%/20%/25%/30%.
- Increased Spirits cooldown from 14 to 20/18/16/14.
- Reduced Tether Stun duration from 1.25/1.5/1.75/2.0 to 1/1.25/1.5/1.75.
- Increased Relocate cooldown from 80/60/40 to 90/75/60.
Alternate color theme, briefly used until the March 28, 2013 Patch