Check my match history on the Illaoi game I just played.

Illaoi V. Gangplank is a skill based matchup

Avoid building on illaoi. It only gives some armor and MR and the "revive" is only useful if you know how to outplay with illaoi with it. Even then its circumstantial and having more health (in addition to some armor or resist), damage, or healing would of been better.

While the boots are helpful, Mercs would of been better still because of the 3 AP champs, 2 of which have strong CC and even Gangplank has a slow from the barrels/Ult.

You had no additional mana from what i can assume, for the early game, meaning you potentially recalled more often you should of. You only had 4 items meaning that you sold your starting item early or rushed without lane sustain. A corrupting potion is the best starting item and i will usually keep it until i finish a mana item. I would always suggest buying a or at least a after finishing your first item (usually this is ). By buying , you can build it into either or depending on the champs in game.

This is my usual build path (usually sold to finish IBG early unless already ahead) .

Against gangplank, i'm pretty used to the Q travel time and can time my W's to kill a barrel right before his Q hits one pretty often. Of course this puts you at risk of being hit by it if you cant time it right. i like to ruin his farming by doing it though.

My primary rune page for illaoi is as follows 9 Flat Armor Seals 6 Scaling MR Glyphs 3 Scaling Mana Regen Glyphs 9 Flat AD Marks 3 Spell Vamp Quints

Between Corrupting Potion, the scaling mana regen, and the spell vamp runes, i have all the lane sustain needed to not recall until i feel like its required. The spell vamp runes also give you some additional sustain in a fight and allow you to heal off the minion waves with tentacles. Its also helps counter-act grievious wounds from a top lane ignite some.

I also, personally like to take Exhaust over Teleport. I find it's utility to come in handy more often than a Teleport does. Especially since Illaoi is about choosing a spot and keeping it. Which Teleport contradicts her playstyle.

Ignite also works but exhaust just gives you more in a fight.

Now, going by the scores alone, Fizz was fed as hell. This would suggest that a would of been a better pick than . While it gives less health, no CD and doesnt affect your healing, the bonus MR it gives would help prevent you from getting bursted down as quickly which will reduce the chances of his from affecting you immediatly from his combo, which will then give you that moment to heal up again.

We can't tell you what you did wrong purely based off that information. All we could tell is if you weren't warding, csing, or playing safe enough.

You could use something like Replay.GG to record your games.

link pls