Illaoi

First Impressions from a jungle perspective.

Unique ?CC? in the form of Test of Spirit. Lack of actual CC and somewhat slow clear speed may preclude her from being a good jungler.

Early clears are somewhat RNG because you don’t always have a tentacle spawn near your location via your passive, Prophet of an Elder God or it may be in an awkward spot. Sometimes you can kite the camp monsters within range of the tentacle but not always. Also sometimes the tentacles spawn fairly late at your location and you may have cleared the camp before that happens or mid lash so they don’t end up contributing damage.

Scuttle crab can be a bit of pain to take. Your tentacles are of pretty much no help unless you get extremely lucky in the scuttles movement pattern with respect to tentacle placement.

My first build I tired 18-6-6 and 9 Arm Pen, sHealth, sMR, Arm + 2 Atk Dmg Quints. Hunter’s Machete and 3 Health Potions and I didn’t feel like that build offered a good clear, though I may need to try it again now that I know how the tentacles work.

The build I finally settled on so far is:

0-12-18 and 9 Atk Dmg, 9 Arm, 9 sMR, 3 Atk Spd Quints. Hunter’s Talisman + 3 Health Pots seems to give reasonably good sustain to start.

Item builds:

Stalker's Blade + Enchantment: Cinderhulk
Tracker's Knife is also a decent option if you feel like you are going to get invaded frequently or want more ward coverage in general.
Titanic Hydra is next if you are ahead or have been relatively unmolested Dead Man's Plate or Spirit Visage if you are having troubles

Black Cleaver after you have some defensive items unless you feel like you need to be even more tanky.

Boots could be Ninja Tabi, Mobility Boots, or Mercury's Treads. She has some engage potential so movement speed can be useful on her for getting into range at the right angle can be important.

6th item situational. More tank something like Zz'Rot Portal might be useful.

You could try building her more damage, but she does have to get into the middle of a fight to do her work, so getting blown-up is a big possibility if you are too squishy.

Given the nature of her ultimate, Leap of Faith, I imagine she would go good with anyone that has a vacuum type ability like Orianna or Diana or an AoE stun or taunt like Galio or Amumu. Which is why I feel like she is better as a secondary form of engage. All in one place? Okay, time to lay the smack down literally.

Ganking

Walk into lane. Jump on them with Harsh Lesson to get a good angle for Test of Spirit. Now the tricky part. Beat their soul to death which also hurts the actual champion and then hope RNG kills them before they can break the curse by killing three tentacles or kill the spirit and then kill them our just outright try to kill them and not really bothering with the soul. Probably cases can be made for all three options.

If you have your ultimate, try and hit as many champions as possible with it. And if you are low on health try and smack them with Tentacle Smash as they try to jump on you or run away depending on their preference.