Welcome to my Illaoi guide. I played Illaoi ever since she was gifted to me by a friend. In my opinion she is one of the strongest top laners there is in League of Legends. I hope you will enjoy my guide and if you do please leave a vote.

Pros

Amazing Early, Mid game.
Good Lane Bully
Great Damage for a Tanky champion
Queen of 5v1's.

Cons

Falls of Late Game (40-50min+)
Difficult to get used to using powers.
Early Mana Issues

For masteries, we take 12 in ferocity and 18 in resolve. For the keystone we take Grasp of the undying to provide more sustain in lane and your ultimate heals a lot more when combined with this.

Runes are quite simple, more AD, more Armor, more Magic Resist,and even more AD. We take;

9 Attack Damage: This will make you a lot stronger early game.
9 Armor: Provides more sustain against AD matchups.
9 Scaling Magic Resist: Provides more sustain against AP matchups.
3 quintessence of Attack Damage: We take this to make your early game a lot stronger and easier.

We max our E first as Illaoi. Everyone might be thinking, why not Q?? Well the reason for that is your Q scales of your present AD. The only thing which changes at max rank is your Q's passive increases its AD by only a little. This means even at rank 1, a level 18 Illaoi can 1 shot minions and etc. Your E provides a lot of poke early game and can get many kills if the opponent hasn't been against an Illaoi too often.

You will want to max your Q first to get that bonsu AD.

Lastly you take W because it doesnt have much use besides the fact tentacles hit the target you selected.

Early Game (2-10min)
In Early Game try to not use your powers too much. The reason for this is you will lack from mana if you use them a lot and its not very necessary. When using your Q or W to attack the enemy, try hitting some minions. Remember you can always last hit.

Mid Game (10-25)
After reaching level 12 (don't quote me on that, not sure after BC nerf) and getting the Black Cleaver, you will be able to one shot minions easily. This will get you ahead in farm even if your a bit behind after a rough start.

Late Game (25min+)
Late Game you should have pushed top a lot and you should be attending team fights. If not keep pushing till you reach the inhibitor turret. THIS ONLY WORKS IF YOUR TEAMS NOT FEEDING. If your team needs help go ahead.

Poke
E - Q spirit - W Spirit - Meanwhile Trigger Passive

1v1
E - Q - W - Q - W

Team fights
E - Q - W - Q

5v1
R - Q - W - W - Q - W = Penta (if not keep spamming powers)