RIP my beloved

For the first 10-15 minutes of the game you play like a completely normal Gangplank. Please do not use this build unless you have at least basic understanding of how to play this champ - he is one of the hardest champs to play in this game and requires a lot of practice to pull off all the combos. This guid is mostly about a specific build, not about playing Gangplank in general.

A quick update, recently the goat himself captain lang d played similar build on stream so now you can watch an example from an actually good GP player!
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Someone at riot did an oopsie and gave Statikk Shiv and Stormrazor a 50% ap scaling, meaning with full build each charged Parrrley will deal 160% ap damage which is A LOT even when you have ~500ap total. Especially considering its a targeted skill. It genuinely ends up being better than most other poke real mages can produce. You also keep most of the benefits of default ap gp - insane heals with one click of Remove Scurvy and ability to win teamfights from any point on the map using your Cannon Barrage.
With this build your Parrrley damage grows exponentially and skyrockets with the last 2 items so get ready to farm A LOT.
I do recommend going for it even though its a bit more difficult to play early because it delays your final Sheen item.

Statikk Shiv is a huge gamechanger as the main problem with ap gp was that you had no consistent way to farm silver serpents required for Cannon Barrage upgrades. Not only it has a good ap scaling and gives you serpents whenever it procs on Parrrley cast, it also has some attack damage in its build allowing you to easily get to that breakpoint when you can oneshot ranges with one barrel (which is Sheen and 2x Long Sword).

If you go for Statikk Shiv + Lich Bane build use 2x Minion Dematerializer on melee and 1 on casters. You can easily q the wave down by exploding a Powder Keg in melee part of it first then just using Parrrley with statik on one of them. Please notice that Statikk Shiv proc is a bit weird so i do not recomend to use it on casters as often its not going to jump through the whole wave if you do that.

If you go for Statikk Shiv+ Stormrazor build, use all Minion Dematerializer on casters as otherwise statikk will be unable to kill them until you get Lich Bane.

First of all - thats to be expected. there are some good matchups (like tur*****fed Yasuo) but most likely you are up against some scary guy like Jax or Irelia. But it doesn't matter, that's not what you are here for. You are here for being the most annoying guy on the map and you dont need to stomp your opponent to accomplish that.
With "secret" Stormrazor into Statikk Shiv tech you just come closer, Parrrley your opponent and run away like a little b you are. Then just repeat until they allow you to farm again.

With Statikk Shiv straight into Lich Bane some of your opponents may be able to punish you if you do the same thing as you don't get that short burst of movement speed Stormrazor provides. Just play like you fed your opponent 2 extra kills. Its nearly impossible to push and extremely hard to dive you so as long as you play safe you will be able to survive till late.

This will sound controversial, but avoid going to your team unless its NECESSARY. One of the best things about your build is being able to help them from any point on the map using Cannon Barrage so abuse that. Just think about it like if you had your Teleport up at all times - always play on the opposite side from the currently contested objective. Even if they try to match you - you are pretty hard to punish because of your Remove Scurvy, slows and decent MS.

As a reminder: if you go for Stormrazor version of this build, join your team once you have most of you items ready. While you can have a little bit of impact in direct combat earlier than that, with this build your Parrrley damage grows exponentially and skyrockets with Luden's Tempest and Rabadon's Deathcap which are your last 2 items.

Keep in mind that your Cannon Barrage is not something you use only to finish someone off. There are A LOT of situations where it may have way more impact. Here's a few examples:

An assassin or bruiser is trying to jump on your ADC? Just ult them to make that a fair fight.

Enemy team is trying to take an objective? Just ult them, they are probably doing that after teamfight and with your help baron will kick their *** more often than you might think. If they are doing that before fighting your team you will set up a perfect teamfight for your guys and give a vision over the whole pit allowing your jungler to easily steal it.

Enemy team is going through the jungle to collapse on your team? Just ult them - they will have to split getting them in a bad position. Of course they can stay inside your ult and lose half their health before teamfight even started if thats what they prefer.

Those are just a few examples - be creative about it! And remember - there is no shame in stealing kills if that kill would be impossible without you.

Those are all mostly for the default ap version of the build as you cant change much about stormrazor one.

Rocketbelt is fine as a Luden's Tempest or Liandry's Torment replacements but those 2 generally feel way better. I can take it if i'm really ahead and want to jump on people like when we had Prowler's Claw for our crit build

This is probably the best replacement for your boots in super late for both stormrazor and full ap builds. The only problem is that i don't think you want to replace boots ever in this build as you become extremely vulnerable.

Extremely underrated item. Even at ~10 stacks its crazy, whenever you are really ahed pick it up right after Lich Bane.

Its pretty good but we do not have enough item slots unfortunately. You can by it with default ap build as a Statikk Shiv replacement in superlate.

You never want to build this dota reference, but there are games where you have no other options. If enemy team is filled with melee champs or just ones really dependant on positioning this item can allow your Cannon Barrage to completely destroy them in teamfights.

The zhonya's into Cannon Barrage is funny, but its usually not worth giving up an item slot for. As per usual, get it only if there are multiple assassins on enemy team and all of them decided to completely focus you out of the game.

It will be godlike in that one game where you are up against 4 tanks with low mobility and will be able to melt them with dots from it and Liandry's Torment combined. Otherwise its not worth it.