Illaoi is incredibly satisfying to play
It's like I'm playing Earthshaker without a stun. Maybe I don't like Hecarim or something, but it's incredibly nice for a physical bruiser/juggernaut to have enormous amounts of aoe.
Her Q is poke, sustain and waveclear in one. W is a great way to stick onto people during ult as well as satisfying to combo with tentacle attacks. I will admit though that I just simply facerolled on my keyboard during her ult. Illaoi just doesn't care who she targets; she'll hit everyone anyway.