Illaoi's Test of Spirit represents everything I hate in game design.

While Illaoi has some odd quirks of her own that I've seen, (can win 1v2 more consistently than 1v1) which I'm perfectly fine with, her E, test of spirit, has several flaws.

Firstly, even if you play a simple, older champ, Illaoi forces you to play a mini game that requires you to have knowledge on her. It's unintuitive and rather than relying on mechanics, it relies on specific information from reading up on the champ. It also relies on allies knowing this information, so they don't steal tentacles for 5 gold. This is by far the worst way to make an ability. Either be oppressive and waste a minute of an ally's time, or have them be devoted to learning specific tidbits of information and waste 30 seconds instead.

Secondly, her E synergises too well with some champs and fails if not impedes completely with others. I'm a CC heavy comp, she has her Q, W and R free but if they don't have lots of damage on an AoE, E is just average. Sometimes, it can even block CC skill shots like Elise's human Q (the web thing that stuns).

Thirdly, if you thought destroying 3 tentacles was the only thing you needed to know, damaging Illaoi before the spirit is destroyed decreases the duration of the spirit by 1 second per instance, letting you go free if the duration ends without you walking out of range or your spirit dying. Not only does the stuff that applies to my first point applies here, this is simply per instance of damage, not a specific amount of damage. This means that champs with DoT like Malzahar and can damage multiple times like Ashe counter her E with no apparent reason, other than the fact DoT applies part of its total damage every half second. It's also probably the only thing stopping her from stomping immobile champs, which sucks even more.

And finally, to rub sea salt on the Nagakabouros inflicted wound, none of these things have visual indicators. I hate having to read up a champ to play against them effectively, I should be able to learn it with intuition throughout the game. This ability singlehandedly makes her the new Yi in low level games, except instead of getting more skilled as time playing LoL goes on to eventually beat Yi in organized teams, you have to spend time reading off game to understand how she works.