Is Illaoi a viable mid laner by any means?

She counters assasins, but she will do poorly vs long ranged mages and you will have shitty waveclear, if they come to push,

I've done Illaoi mid before, she can stack her passive tentacles in a lot of places and when ganked just like Heim, she can kite around her tentacles like how Heim does with his turrets.

I like going Gauntlets first item against AD midsas it gives mana/armor and as well a slow which works in her favor NOT to mention CDR and yeah you get the picture. She takes a while if going against a bully champion who can force her off cs'ing but then you could max Q for long range cs'ing which for me I'm more aggressive so I rather max my W and just poke with my tentacles.

For AP mids I would first rush Spirit Visage.

Doesn't hurt to play a normal and test it out! Best of luck!

She's great at mid just focus more on dodging the enemy midlaner's attack before counter attacking but she's a good melee to take mid cause of her range and farming potential.

Absolutely Cho gath, ryze, swain are tanky dps like illaoi. Granted AP. But if your top or jung is an assassin then you can put a bruiser mid screw meta trying to mess with team comps

She has great push. About her only redeeming quality in mid. If you fight something like Zed you're in trouble, as he can infinitely push and ult you then shadow away if you counter ult.

It definitely does work. With armor and mr runes, you're able to go up against my different mages and ad champs. Although I haven't gone against many ad champs at mid lane, she can strategically spawn her tentas at the four pillars of the river to be able to prepare for ganks.