Abilities of Illaoi
Spell skill priority is an important winning factor for Illaoi. Understanding the abilities of Illaoi in League of Legends is another. Below you can find all the relevant information on Illaoi abilities. In order for item builds you should check the build for Illaoi.
Passive: Prophet of an Elder God
Illaoi and the Vessels she creates spawn Tentacles on nearby impassible terrain. Tentacles swing at spirits, Vessels, and victims of Illaoi's Harsh lesson. Tentacles deal physical damage to enemies hit, and will heal Illaoi if they damage a champion.
Tentacle Smash
Increases the damage dealt by Tentacles. When activated, Illaoi smashes down a Tentacle that deals physical damage.
tentacledamageamp*100% (currently f1 physical damage).
Harsh Lesson
Illaoi leaps to her target, dealing physical damage and causing nearby Tentacles to also swing at the target.
Illaoi's next Attack causes her to leap at the target, dealing an additional healthpercenttotaltooltip max Health physical damage. When she strikes, nearby Tentacles will Slam at the target.
Test of Spirit
Illaoi rips the spirit from a foe's body, forcing it to stand before her. Spirits echo a percentage of the damage they take to the original target. If killed, or if the target gets too far from the spirit, the target will become a Vessel and begin spawning Tentacles.
Illaoi pulls the spirit from an enemy champion for spiritduration seconds. The spirit can be damaged like a champion, with echopercenttooltiponly of that damage echoing to its owner.
If the spirit dies or the target leaves its range, the target becomes marked for vesselduration seconds and is Slowed by slowamount*100% for slowduration seconds. Marked enemies spawn Tentacles every f1 seconds.
Tentacles will automatically Slam at spirits and marked enemies once every timebetweenvesseltentacleslams seconds.
Leap of Faith
Illaoi smashes her idol into the ground, dealing physical damage to nearby enemies. A Tentacle spawns for each enemy champion hit.
Illaoi smashes her idol into the ground, dealing damagecalc physical damage to nearby enemies and spawning a Tentacle for each enemy champion hit.
For the next duration seconds, Tentacles are untargetable and Slam 50% faster, and Harsh Lesson has a 2 second cooldown.
FAQ on Illaoi
What do you max first on Illaoi?
Most Illaoi pros max out 
Test of Spirit first.