Illaoi has counterplay
Getting kind of tired watching potato top laners do everything wrong vs Illaoi, so if you're someone that's struggling with her or you're one of the people on boards claiming she's cancer, here are some tips beyond the obvious 'dodge her shitty slow skillshots'
E and W can be canceled by displacements. It's obvious for W, but not for E; if you hit her with a knockup or anything similar while her pull hasn't reach you yet, the entire spell will cancel. This is important; landing spirit grabs is what makes Illaoi win trades and 1v2/1v3 with ease. Q doesn't work this way; she can throw a Q if she's expecting CC, it will still hit that area; be wary.
If you get grabbed, and you can afford to fight her, move to the sides of any incoming tentacles about to hit your spirit. I'm genuinely surprised by how many people let Illaoi get double-hits on them by not just moving out of the way. If you have ranged harass or a DoT you can drop on her, even better; any of that stuff will massively reduce her chances of putting a vessel on you.
Illaoi is immune to displacements when she ults, but only on the way up. Don't be obvious with when you're going to try to InSec her, Mr Pro Lee. Bait her to ult first, then kick her. Works the same way with Singed flip, Flay, Janna's Q and R, etc.
If she lands a good ult and all your peel is on cooldown, the best thing to do is to spread out. Someone will probably die to her if their mobility/Flash is on CD, but it's far preferable to you getting close to whoever she's focusing and getting killed by her AoE. Pay attention to where Illaoi's moving; you'll know who she's gunning for. Don't try to be a hero; unless that person is more important than you are and it would be worthwhile to pull Illaoi's aggro to you, run away.
Stacks?
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) has an obnoxious tank stat as his passive. Not only that, Illaoi definitely falls off late game, perhaps even more than 
, who although kitable can Flash+E for some rather cheesy but still workable engage.
on Illaoi is stupid strong in the right match ups. Typically is a great item vs Darius. Maxing W vs Darius combined with IG typically does great burst damage when he tries to go In on you while near her passives. Vs Darius rush IG, max W, and make sure you never fight without landing an E.
I don't think I'll die before getting out of range.
(replace BT with Sunfire Cape, GA, or Randuins if you want).
. He has enough mobility to usually dodge her E, but if for some reason she does land one simply W out of there tanking all the shadow damage and start over. If she ults while toe to toe either W out of her ult, or ult her out of her ult. She won't do damage if she isn't near her spawn.
can beat her. That's right. Teemo. Avoid the Q's and blind her when she's trying to W your Shadow. Most of the time you can keep her off farm early and get enough of a lead that she won't be much of a threat after 6. Teemo also has the uncanny ability to kill her passive from a ranged distance so while she is blinded trying to hit your shadow, you kill her tentacle and prevent further damage.