Illaoi's soul thing is bs
It's fine early game/laning phase when you can actually fight back fairly to not get cursed, but late game? You're vayne, you get our soul pulled out, and there's legit nothing you can do but hope to god the tentacles NEVER get in reach. You dont want to go in and fight that bitch, none of your team is ready to fight and you're initiating a teamfight against the top laner as an adc.
or any champs that take advantage from hitting that crucial spell. When she grabs it dont let her have it without a fight, early game you can harass her making her decide what she wants you or the soul. Counter pick and win the test with a AA reset champ and its okay, learn the ins and outs and you are fine.
Are great choice against her.