Illaoi
Hey, get the **** out of the tentacles when she uses her ultimate. Personal experience, seeing others under her ult, and even watching this fight between
P1 and NRG where an Illaoi, Quas, defeats 3 of his enemies. She not only gains health from each tentacle hit, but she deals MASSIVE damage to champions. YOU WILL NOT SURVIVE (unless you break out your all) under her ult.
What I do is just poke her down, avoid her slams and grabs (obviously learned after a while) and bring out her ult when I can. Once I bring out her ult, I immediately step out of her circle, which eliminates her ult's use, unless of course there are more tentacles around me. Without her ult, she is back to useless, as far as massive damage goes. Once her ult is down, re-enter the fray.
Tbh, it actually feels like mundo's, zilean's, or Trundle's ult, where they gain massive sustain, but instead, she is able to gain MASSIVE damage, within only a few seconds. You obviously don't have to listen to me, but be aware that her ult will kill you, in just a few seconds, and will keep her sustain up.