Hold hands with your laning partner at any time you can. Any health or mana regen you get will transfer to your buddy at a 1.5x rate, which is sexy, but keep in mind that only happens when you're actually regenerating, not at full health. (Max this quickish if you will be relocate-ganking a lot)
Don't ever detach the tether, unless you're using Relocate to teleport a buddy to the battle, but not staying yourself. If you time the recharge right, you can tether someone in, untether, grab someone who's who about to die, then teleport out to saftey, effectively tag-teaming your teamates.
Only really powerful early-mid game, but they bend creeps over and maintain lane dominance. Keep in mind you can't untoggle distance while silenced. Use this especially when there are cloaked heros or copies around to find the real target where the spirit bursts. Also good for killing straglers.
Overcharge is a MUST at level 2. With this, you can force damage on yourself so your buddy gets the healing he needs, as you can't heal him if you're not actually receiving health/mana. Also good for saving heros, as it gives a good damage reduction. (Decide to max either this or Spirits first.)
Easily one of the most adaptable and frustrating skills in the game. Use this in combat to teleport to spawn, grab items and heal up, and jump right back into combat. You'll want to stay alive and keep your buddy in lane until you get this instead of running back, since you can teleport.
These are tricky to get used to. If you're having difficulty getting good hits on heros, focus on moving around rather than changing the Spirit distance.
Remember to keep them close to you if you think an invisible hero or illusion is nearby, they'll pop when they hit the real hero.
Starting Items
Airdrop this immediately. You're the support. Emphasize that shit. Unless, of course, someone else is also playing a support. In that case, get them to buy wards too. You should focus on protecting and powering your hero.
Always keep a few potions on you until you get the bottle. Remember to have your teamate cast his potions on YOU. If you've got overcharge, you can always give your buddy 600 hp while healing yourself 400.
Not sure where Io wears this. Maybe it all just floats around inside him. Anyway, this will lead you into the Headress.
Early Game
This completes Io from early game. The temporary mana transfers as a regen to your tether, giving them 225 mana without taking it away. This helps you limit your use of Overcharge outside of teamfighting, and is extremely useful when paired with Mekansm.
Now these things are even nicer. Boooooya. Prioritise never attacking and staying on the edges. The insane hp regen rate on these babies and sexy speed boost will keep you moving. Mash that 'S'top! key to make sure you don't auto-attack!
Core Items
Aether Lens is a wonderful addition to the Io lineup. In addition to providing a bigger mana pool and increased health regen (which is always good) your tether gains an increased casting range. This is very useful for keeping yourself on top of your tethers, even at a range.
TIME TO FUCK SHIT UP! But no, seriously. If you recover the maximum amount of health while tethered, your buddy receives the Mek heal AND the bonus from the tether, up to a maximum total of 625 instant heal! Paired with Soul Ring, be ready to pump 625 hp and 225 mana into your friend instantly.
Great for the hp regen, even better for the 400 damage shield against spells. If you're running into a teamfight, make you sure you time when you drop this to prevent heavy damage from attacks like Lina's ult or Lion's, or even Shadow Shaman's basic.
Items for Winners
If you're having trouble with certain casters, silence them and stun them with your Tether, then smash them with your partner and Overcharge.
At this point you should already have won the game. If you've got the coin now, get a bloodstone. You'll never have to worry about mana, and neither will your tether. If you do end up dying, the health boost to your allies helps them all escape.
Mostly for mana and hp regen, but the spellblock should keep you from dying completely, since you should only be taking damage rarely anyway.
A pretty decent item for Io if you've got the money and no one else on the team is making teamfight items.
Situational and Alternate
Use the bottle for mana at first, which will always be low if you and your lane partner are playing agressively. Coming mid-game, you're partner will be soaking up more damage than you will, so pair this with Overcharge and Soul Ring so you can be healing them even while you're at full hp in fights.
Pretty slow regen, so not very worth it, but remember, your buddy will be getting 150 mana instead of the bottled 100. This is definately good for early game support, since you won't need to use Overcharge and hurt yourself to be giving a mana boost and can instead retether or use Spirits
If the enemy is using a lot of skills in your lane, this is a definite must. You'll be able to recover mana and health instantly, and your buddy can get a max of 337.5 hp/mp in a full charge.
If you're noticing that mana is an increasing problem, build into arcane boots instead of the Tranquil boots. Using them while tethered will give your tether bonus mana, up to 202 in one burst, not including the bonus they get themselves. Definitely helpful for mana-heavy tethers.
You shouldn't be dying at all, so the gem is great for Io. Take this in place of the Medallion if you need it.
Combine Relocate with wards, and you can instantly have good vision without risking time or a gank. Typically place them in the key spots, like the rune lookouts.
If you've got the money, pair up your wards with sentries so you can see all those pesky cloakers.
Building Armlet is entirely up to you. After playing a lot of Io, I've realized that keeping health low enough to maximize tether regen rate gets difficult late game, forcing you to enter battle to take damage. This is obviously a risky, bad idea. Other than the HP drain, it doesn't have much use...
Other Items
blink dagger? I suppose this could be useful. I can think of a few ways to use it with Io, but none really necessary.
Again. No. Never get a straight damage upgrade on IO. He doesn't right click in nearly any situation.
Builds into Mekansm. That's about it.
If you've got the money, but you're still taking a beating, this item will help you survive, while also buffing your tether buddy's heal rate. A good buy.
No. You can't buy items FOR your carry. Though that'd be awesome.
Fuck yeah. Armour. Uh. Can't remember what it can be used for off the top of my head, but it's expensive, so don't get it unless you're building into something.
Eh. Well. It's a thing. A thing not really for Io.
These are neat. Instant HP regen to your teammate.
An interesting little item to help you survive some nuke damage early game. I've not tested it myself, as I prefer not to rely on consumables, but I could see it being useful.
Io shouldn't need the extra speed with the tether, but you might need this to complete a Euls or something.
Basic armor item used for some recipes.
Consider a shield if you're really having trouble with harass. You should make every attempt to NOT negate damage, though. You need to lose some HP. If you've already got soul ring but having a hard time, this is an OK buy.
Decent early game item if you already have Soul Ring. Always go for Soul Ring first. Personally, I don't think any Io build is complete without a Soul Ring.
No real excuse to be buying agility slippers.
Mantel is nice for some extra mana, but it's not really necessary.
Not a whole lot of reason for branches in this build, other than to complete parts of the core build. This build focuses on learning how Io functions and maxing up his heal rate.
Still no need for agility.
A nice item, but remember: If you're not using it to build into a support item, there's no reason to buy it.
While STR is Io's primary stat, it's not necessary to get this unless you're building it into something.
Builds into a few useful things. Nice for the int boost.
Delicious mana regen rate. Helps you and your tether.
Boots make Io go fast, like sonic. When tethered, of course. Don't bother buying them until you have a few more items, though. Roughly 15-20 min in, boots can still be bought without suffering much in game.
A good item for any hero when taking heavy nuke damage. If you plan to build into pipe later, grab this as well.
Not needed unless you really need that halberd.
Wand is good. Good wand. Good.
Very situational. Probably a bad idea.
Mangos aren't very cheap, and probably aren't worth it if you rush a Soul Ring like you should.
Dust of appearance is best when used when it's best used, which I hope is obvious. This is a support item. Use it as needed.
(Don't actually buy this.) Tangos are nice, too, but typically are given to you by your lane partner, rather than bought yourself.
No real reason for Io to carry around TP scrolls past early game, but if you have room for it, it never hurts to be ready.
BoTs? That's just excessive.
If you're REALLY having trouble keeping up with your partner, this is the only excuse to get these. Otherwise they're an expensive waste.
Only ever possibly useful with an AC, and even then it'd be much better on another hero.
Good for HP regen, but make sure you're building it into something useful.
Good for mana regen but make sure you're building it into something useful.
Not really worth it in all honesty.
Hahahahahahahaha! HAHAHA. Ahhhahahahah. But no. Seriously. Never do this ever.
Builds into some nice late-game stuff, but probably not stuff for Io.
A good buy! Just boosts the bonus Io gives.
mer. It's okay. don't bother though
An okay buy! Live longer and probably build Drums!
Anything aura is great. Use this to make sure your team is drinking up most of the blood it spills.
Pretty nice if your lane is having bad mana issues.
Urn's a good idea, too, if you're doing okay and need to support more than just on wards and your pocket-heals buddy. Cast it on yourself most of the time.
Anything aura is fantastic. You'll give your teamates the bonus as well as yourself, which stacks and even becomes more potent when you're damaged and tethered to others. This will lead into Mekansm, which is the first item you're going to want to build into after bottle.
The Scythe is the best kind of "fuck you"
Eul's is good. Good. Movement, disable. Good. Notsomuch good for Io. Leave it to your other support, which there SHOULD be another of, like semi. You can pick it up if you really need it, though.
I suppose there might be some cool tricks you could pull off with Io and the Force Staff. I'll test it out, see what happens.
A pretty neat item. Adds range for you if you ended up right clicking. Probably not going to end up getting it, but it's not useless.
Hahahaha! Worth it? Rarely. Still. Dagon Io is funny shit.
Necronomicon is a good pick for the Int and Str boost, as well as for true sight later on, but I still feel like this is an item better used by other heros on the team.
This is overkill. You definitely don't need it.
It's got an aura. You should have it if you've got money floating around inside you and no one else has taken it.
Only buy a heart if you're winning really hard and just want to be an asshole.
Shouldn't need a BKB but, very situational.
Shiva's is nice but Io is a strength hero.
Very situational, probably best to avoid it with Io.
Maybe useful, but you're not trying to be a tank as Io.
Might help convince people not to target you, but other than that not worth it.
Gotta get this to get pipe. A great boost of magic resist.
Hilarious idea, but you'd become too much of a target.
This doesn't make any sense.
Io isn't suited for right clicking.
Hmm. Possible. A waste of money, though. It's better to have good team coordination than to use cloak.
Get a heart instead if you really have to.
Sorta useful, but not when you compare it to pretty much any of your other options.
Hrm. Well. No. I'd say don't.
Not useful at all for Io. Even if it reduces the cast time, you won't be benefiting from it much.
Not a bad idea to help keep pressure up in lane, but a bit too expensive to justify. With the health boots, you'll be hampering your hp regen if you're right clicking.
Hrm. Well. Drums are cool. I guess. They're a good support item, but with the stat boost, it should go to someone else who needs the points.
A cheap buy, and a good bonus to mana regen. Not always required. By this point, teamfighting should be getting much heavier, so keep this on a good key so you can pop it off on whoever you and your buddy are targeting.
Certainly a neat item but just not useful enough.
Truth be told, Io doesn't have a lot of use for this. With Relocate, concealed travel isn't too much of an issue.
This could be useful for helping Io catch up in levels with the team, however, that's gold better spent on support items and the XP is in better hands elsewhere anyway.
An awesome item for Io. Regen? Yep. Int boost for mana? You bet. Teamfight support debuff? Fuck yeah.
Delicious Guardian boots. Wonderful on a late game Io if you built mana boots instead of tranquils. It's possibly even worth selling the tranquils for if you're making good money and already have plenty of regen.
Decent. Good for the int boost, but still not a perfect item for Io. In terms of ability, it's definitely good. It's a big fuck you to the guy you're abourt to tether-stun.
No reason for Io to have this.
Actually not a terrible item for Io considering the strength boost, evasion, and the ability to disarm, however it's very situational as you'd be better off with teamfight or regen items.
Ring of Basalilisusfgasdhu +1
Very unnecessary for Io. You wouldn't benefit much at all from the invisibility.
