Completed! Full and throughout guide and Let's Talk on Io. But why?, one may ask. You can just play her and figure out what works for you. Because, you can read this at work while bored.
Will make sure to update this once the new patch goes live.
-Abilities and Ultimate : Begone!
-Best team compositions / Worst counterpicks
-Niche tips and tricks
-Cards and Items
Io has been around for a while, and has already captured hearts of many. With the unique ability to fine-tune her healing to extremely precise amounts, she is becoming a very popular pick that can rock with any team composition.
She is super versatile and a well-rounded character, bringing a little bit of everything to the table. She really is a jack of all trades, but master of none, and should be played as a very reactive champion. Unlike most other supports, Io can command a very strong presence in fights, but her greatest weakness lies in being extremely team dependent.
Io's talents are : Life Link, Goddess' Blessing and Sacrifice.
Life Link : Luna now heals allies near her. A nice talent if the enemies have a lot of spam or area damage that can decimate your Luna in seconds if you try to place her on point. With Life Link, you have a personal bodyguard for you and any nearby allies, that can also double as a point healer/capture once you decide to dive in with your flank or damage.
Goddess' Blessing : Allies you directly heal take a quarter less damage from any sources. This talent really shines through both early and late game, due to the fact that Cauterize counters heals - but damage reduction is always persistent. This build does yield less overall heals than Life Link (about 30% less stat-wise), but makes up for it as it blocks a whole lot of damage (all the while you heal them).
Sacrifice : If you die while Luna is active, she is sacrificed, you take her place and heal. Heavily overlooked talent that isn't all that bad (who doesn't like a second chance) - the reason it's very rarely used is because the first two talents bring more value during the fights, even if you rock a more aggressive play-style.
Abilities and Ultimate : Begone!
Tho shy at her release, Io plays grew tremendously as time passed by and players started maximizing her potential. Foolish be that off-tank who dares flank an Io player with good positioning, as he'll just be yeeted off the map to shame eternal. Nowadays, it's not uncommon for Io's ultimate ability to make or break games, as she eliminates an unsuspecting enemy. or two (even going as far as getting a full team wipe myself (with my dear Seris friend <3)). Leave this realm, cuz this one's ours.
Her standard abilities can also make plays. Her default healing isn't strong, but is reliable and maintainable. Learning to weave in attacks in between Moonlight heals, to prevent straight up burning through it (you don't have to top every all to 100% all the time, most times you can afford to wait even a few seconds before healing them the 300 hp they're missing), is a must. Running a card that grants more Moonlight for landing attacks will trigger even on deployables and shields, making it a reliable source of regeneration. Her healing lingers for a little while after target exits your line of sight, making her an extreme corner hoe. Any corner is a reliable positioning for Io, as she can use Luna to call for a strong defense.
Luna is a very nice companion that, while very often used as "What you leave on point so your team can push enemies back", it's use is only limited by player's creativity. You can place Luna on a suspicious flank as a warning to whoever might be coming. Early game especially, Luna really is another character with persistent auto-attack and whooping hit points bar, making a game 6v5 up-front. Remember that you can see your Luna's hit points near your character portrait, and don't ever leave her to die or sit idle forgotten half-way through a push.
Always keep Luna around you, as you can land stuns on overextended enemies. The stun will go through many obstacles (It stuns enemies out of shields if you hit them directly (Nando, Khan), Luna can pass through most deployables (Ying's Illusions, Inara's Wall), ignores cripple ((Tyra's Fire, Imani's Volleyball)). It really is a nice stun that allows you to either set-up for an ultimate, run away, get a few shots or save an ally. Oh the choices!
Last but not least, her leap. It's your best ally and your worst nightmare. If you happen to decide to play a lot of Io, you will start to hate tight maps like Brightmarsh - what a nice little jump OOF, you've hit that aqueduct. You going nowhere yo. Or remember that time when you've yeeted yourself off the map? Or that one when you've almost got a triple kill but your jump got stopped on an environmental rock, size of Barik? Learn to never panic-press the jump. It's cooldown is too long to be used as a lucky bail-me-out card, and it's not reliable nor it grants any invulnerability. Learn to look around and bellow you you, choose an angle, jump first and then leap for maximum distance and momentum.
-Best team compositions / Worst counterpicks:
Io works best in team compositions where she has advantage of free middle ground. If her damage and flank parts of team are able to maintain line of sight on her at most times, she can be present in all fights at once, very effectively, all the while capturing the point. Therefore, Io's positioning should be as central while as safe as possible.
Io fits in with any team composition, duo-tank or single tank, and she also works wonders with double support comp.
Her best team composition is two off-tanks, herself as support, and two free characters, best if both damage.
Io's worst nightmare is the Blue Orc, as his chain lightnings eat through Luna's hit points and force you in a position where entire team needs healing at once, and that's Io's weakness. To counterplay your counterplay, make Luna bodyguard unsafe flanks instead of being in his sight. That way, she still gives value while not frying your team for being a sitting duck.
Io's other counter is Zhin. He can follow you through any distance you cover with leap, and he has two immunity abilities that let him reset or resist Luna's stuns. In most 1v1 scenarios, Zhin wins, even if Io player tries to dance around Luna and pump her bow. The only times Io wins is if she can spot him before he's too near.
-Niche tips and tricks:
-Learn to be patient. Time Begone! to work when the enemy has no CC (i.e.: count to 4 when you see Inara pop her CC state, or when Nando ults). Don't waste the ability to try to defend yourself from a flank you got caught - it's mostly going to be a waste. Instead, learn of the map's environmental edges, and try to position yourself for a VERY clear shot. For this reason, you are absolute counter-pick to Ash - when and if she tries to dive you, a well-timed ultimate will not just eliminate or stop her from her field, it might also yeet her off the map.
-Best map for Begone! plays is Splitstone Quarry, with the flank from the Lava Mill right into the blades in the mines. Gives enough cover for a nasty surprise. Sadly, for some reason, you won't get credits for kills, but whatever makes 'em go down, yea?
Cards and Items:
Io has a very niche selection of cards to suit your play-style. These are suggested loads for first two of her talents that you can base your builds around, and then fine-tune them to your play-style. There's no direct builds for Sacrifice, as either of the two main builds (or combination of both) works perfectly for it.
With that being said and considering the total time you will be spending healing allies with Moonlight, I strongly suggest to keep Swift Arrows on either IV or V - it's a very powerful card that sure is a lifesaver; and have Restored Faith anywhere between III and V (I personally think anything over III is countered very heavily by Cauterize, so the points went in other cards that have no direct outplay).
Reduce the Cooldown of Luna's redeploy by 0.4s after healing with Moonlight.
Regenerate 8% Moonlight every 1s while within 30 units of Luna.
Reduce the Cooldown of Luna's redeploy by 0.30000000000000004s after healing with Moonlight.
Reset the Cooldown of Lunar Leap after dropping to or below 45% Health.
Heal for 10 every time you Heal an ally with Moonlight.
As Luna gains a healing aura, Life Link build revolves more around personal survival and improving all your abilities. Spirit Arrows III allow you to constantly reposition Luna around, doubling her as a second healing ability. Since we will be moving Luna around a lot, we have Crescent III as a quality option if we happen to get caught off-guard by a flank.
This build suits defensive teams who can protect you and Luna.
Increase allies' Movement Speed by 40% while they are being Healed by Moonlight.
Reset the Cooldown of Lunar Leap after dropping to or below 45% Health.
Heal for 30 every time you Heal an ally with Moonlight.
Generate 6% Moonlight for each enemy hit with Light Bow.
Reduce the Cooldown of Luna's redeploy by 0.1s after healing with Moonlight.
With Goddess' Blessing, we need more up-time on Moonlight and a way to generate if faster once we run out of juice, hence Moonlight Garden III. With this build, we also don't need to move Luna around too much, she can help with point captures, babysitting your backline from flanks or just guarding a certain area. We also have speed buff maxed, a little bit of self-sustain, and a reliable rest once we get to half of hit points.
Filler Card is Spirit Arrows, or Moonlight, which is a one-point wonder much like Ying's Rewind, and allows you to double distance covered with your jumps if you need to escape or catch up to allies.
This build suits a more aggressive team and play-style.
As much as they are personal preferences, these are key items to keep in mind come to Io's play-style.
Gain 21% Movement Speed.
Reduce the Damage you take from Area of Effect attacks by 21%.
Reduce the duration and effectiveness of Crowd Control and Slows by 60%.
Reduce the Damage you take from Direct attacks by 21%.
Your weapon attacks deal 60% increased Damage to Shields.
Increase your Ultimate charge rate by 30%.
Nimble allows you to maneuver around fights, either to catch up to allies you're buffing to oblivion (32/40% movement via Swift Arrows), or for quick dance-peeking around corners so you maintain heals on allies without being exposed for too long.
Morale Boost gives you more chances to either yeet an enemy off the map that's trying to bring you down, or allows you to use this ability more literately to dodge some key ultimate abilities, as it does provide a very brief immunity that can save you from, say, Viktor or Dredge ults if you REALLY need to be alive.
Haven, Blast Shields and Resilience should be picked up if certain enemies give you more trouble than you're comfortable with.
Wrecker is very often overlooked with Io - but even Wrecker II allows you to apply a whooping 1.000 pressure pokes against shield-heavy compositions (with Io's very fast attack speed, you can quickly eat shields to land a stun with Luna if necessary).
Reduce the Cooldown of all your abilities by 30%.
Increase your Reload Speed by 60%.
Chronos does not benefit Io too much - chances are if you get caught off-guard, 3 seconds off your Leap for whooping 2400 credits isn't doing you any justice; neither it helps Moonlight's resource bar in any way. You are much better off grabbing another item from the list above.
Deft Hands also shares the same reasoning - there are other items that give Io much more value, and considering she already has a rather fast reload animation, it's just not needed.