As an aatrox, I can bully her out of lane and can kill her if she over extends until she's level 6 and complete fucks me when I fight and she ults, the healing from her tentacles is insane and executioner's doesn't affect her healing at all. And no dodging her E isn't counterplay, you can say about any champ with a skillshot.
kill her tentacles (try) to dodge her E do not fight in her ult. You're going to lose.
leading and dodging a key skillshot is always counterplay. this isn't like xerath Q or ezreal Q where they have it back up in 2 second late game. You dodge it and then she's vulnerable to getting smacked down for the next 16-12 seconds before CDR.
Early game you don't let her freeze at her tower because then she's safe from ganks, later on in lane you want to start pushing so you can clear tentacles so that she can't maintain her safety net. Bait her ultimate and leave and all in her when its down because she NEEDS ult to win post6 fights
when she ults just move out of the general area, either her ult is wasted or she chases into tentacle-less terrain, making her an easy kill
Answer: You don't.
Man this is like asking "How do you gank heimer without giving a double kill?" No one actually knows...
Illaois biggest counters are scaling and walking away.
Leave her ult when she uses it, unless you can burst her in literally the next second. Make sure the rest of the team knows this too, when Illaoi ults that's HER space for the next 8 seconds. Unless you put some long lasting cc on her and pop her before it wears off (unlikely if she builds right).
For the most part, lane to live. If she's not ahead after lane phase she's easy to handle. She deals no damage to tanks without feed and E, any ADC can safely hold lane against her split and scales better with farm.
Look out for flash ults, in which case go back to point 1. Don't try to ignore Illaoi and finish baron, turn and kill her if you can.
And dodge her stuff. Executioner does help, but GW isn't 100% effective, she heals just that much.
