Intro

There's quite a few Io guides up on this website right now, and I've seen a few discrepancies between them all. I'm a support player with a >70% ranked win rate on Io with almost 150 games played across 2 seasons. I also have experience playing her in high tier scrims/PUGs. This guide is going to hit you with some quick tips that will instantly improve your Io gameplay. For a TL;DR, read the bold statements! :)

Maximizing Io's Value

Talent Choice

First, let's talk about talent choice. You should never run any talent other than Goddess' Blessing. The most common talent in lower ranks seems to be Life Link. It's important to recognize that running Life Link disallows you from capitalizing on Io's greatest strength, which is that her dog captures objectives for you. When you use Life Link, you're forcing your team to play around the objective when you could instead be taking space and zoning. The common response to this is "but I get more healing with Life Link!". While your total healing numbers may be higher, there's a bit of a catch there. Late in the game, when your enemy has cauterize 3, your dog will lose almost all of its value, healing for only 50 health per second. Your moonlight will also drop to 37.5 health per 0.15s. Both of these numbers are extremely low. However, if you run Goddess' Blessing, you're ALSO giving your teammate 15% damage reduction. This gives them a much greater chance of living. Also, Sacrifice is a throw because you don't get extra healing or damage reduction. Don't run it.

Choosing a heal target

Another big misconception about Io, and supports in general, is that tanks are your main target for healing. Good support players keep all of their teammates alive. My absolute best tip for Io is to heal the target with the lowest health NUMBER, not the lowest health PERCENTAGE. Here's a scenario. You have an Androxus and an Ash on your team. Your Androxus has 50% HP, and your Ash has 30%. Your first thought may be to heal the Ash, but in this instance, your Androxus needs the heal more. Since his health pool is 2100, he has 1050 health. Ash however, will have a minimum of 1350 health, assuming she isn't running an extra HP card. Your Androxus actually has less health. The big idea here is that tanks can take more damage because they have more health. Obviously, there are other factors to consider when choosing a heal target such as whether or not they have cooldowns, where they're positioned etc. but this should be your main concern. You can also heal your dog if it's the only one on point to buy time, but if you're the last one left and there's time to regroup, move it off of the point so it can regenerate on its own without you wasting resources.

Positioning

Io, like most other supports, should be positioned behind her team most of the time. To maximize your safety, play behind walls. Io's heal lingers after you move behind a wall, so use this to repeatedly peek someone who needs healing while remaining in a safe position yourself. You can also abuse short walls/fences in the same way by jump peeking. This is especially strong on Bazaar, for example. You can jump next to the walls surrounding the point repeatedly, which makes you much harder to hit, as long as there isn't an enemy on the high ground that can directly see you. Io's greatest strength comes in the form of her dog capturing objectives. After you win a team fight, put your dog on point and have your entire team move up to knock the enemy off of their horses. Position yourself aggressively, but in a position where you can fall back if you lose a teammate or if you capture point, so you can place your dog on the cart. You should continue to have your team play extremely aggressively until you lose 1/2 teammates, depending on who you lose first. As soon as you lose them, start to back up to the point so you can secure the capture. Lastly, don't stand in front of a wall that you cannot use your movement ability to jump past. This puts you in an extremely vulnerable position as you won't have anywhere to escape to with your movement.

Io's Ultimate

Io's ultimate is one of the weakest in the game. I have my ults get clipped on walls that are nowhere near me all the time. On top of how buggy it is, it also doesn't provide much value. You're forced to use it to get environmental kills or to deal 800 damage. Regardless of this, it's still possible to get value out of her ultimate. There are a few maps in particular that have extremely consistent positions that are guaranteed to net you a few kills listed below. These maps are Jaguar Falls, Fish Market, Frog Isle, and Serpent Beach. There are 2 spots on Jaguar Falls. The first one is playing on the side of point that is not open, which most people refer to as dark. If you are able to safely move into this position, you can slide your ultimate on the floor, up the stairs, and out into the void that is on the other side of the point. The reason you shoot the ult at the floor rather than straight is that by shooting it low, the ultimate will drop them much closer to the void, making it more likely they die. The other ultimate spot on Jaguar Falls is in either spawn. I've gotten tons of cheeky kills here. If you're defending, you can play near your spawn and shoot it straight out into the void that's in front of you. If you're attacking, you can earn some style points by using your movement ability to jump behind the enemy and ult them off of the map. While this is extremely risky, it's often unexpected. I've gotten 4Ks doing this. Next up is Fish Market. The area that you should be looking to use your ult on this map is in the straightaway area on both sides of the map, right before the bend that takes you into the very open section near the spawns. There's no map geometry for the enemies to land here, like the docks near the point. Frog Isle's position is similar to Fish Market's. Use your ultimate near your spawn, down the straightaway. Most enemies will be in this area, and there's no geometry to mess up your ult. Lastly, Serpent Beach also has a good ultimate position near the spawns, since there's such an open path to the voids. With the exception of the Jaguar Falls point ult, you should point your ultimate into the air more often then not. The hitbox for the thing is HUGE and pointing it up will both catch enemies relatively consistently and stop it from hitting weird map geometry that's present on most ledges.

Advanced Tech

Obviously, you can use Io's movement ability backwards to quickly move towards your team, away from an enemy, etc. However, there's a few tricks that you can abuse to make the most of it. First, face a wall. Get close enough to it to trigger a high jump, then instantly 180 and use your movement ability. This can be used to gain lots of height and get onto certain high grounds in the game that are relatively difficult to land otherwise. Examples include the Frog Isle window and Serpent Beach point high grounds. Another tech worth mentioning is how to consistently save yourself with your dog. A lot of Io players don't realize that even when your dog isn't deployed, when you hit an enemy they still are marked with the stun, even though the game doesn't show it sometimes. What I often do is hit an enemy and then instantly deploy my dog. This accomplishes three things. One, you can use your dog to bodyblock, potentially saving yourself. Two, you can heal the dog if there's no teammates around, giving you self heal since you should be running Restored faith. Three, it stuns the enemy, giving you a chance to heal even more or have a teammate come help.