This is my way of building Gangplank. It works for me, literally 90% of the time. What I mean by that, is in 9/10 of the matches I play with him, I end up carrying the team, pretty hard. No I'm not just saying that to brag, it's the truth.

Since Gangplank is a damage dealer above all else, I put 21 in offence. Focusing on the cooldown over the attack speed. As attack speed won't be necessary with this build.

The rest are put into mana related masteries. This is due to the fact that if you find your self getting pushed really hard early game, you'll need to be able to spam your Q to get them to back off, or just harass, and while it isn't the costliest spell in the game, spam anything enough times, and you'll run dry on mana sooner or later.

With this set up, even when soloing. I've never had a problem with mana. Even if I'm getting pushed into my turret hard. I can spam my spells to push back a bit, stand back while they push again, and by the time their new wave arrives at my turret, I'm at about 1/3 mana again. So trust me when I say that you should have no issues with mana.

Why mana regen? As stated in the masteries section. This will help you never run out of mana early game.

Why not mana regen per level? Simple. Because there's no point to per level mana regen runes. Ever. Runes and masteries are generally meant for early game assistance. Mid-late game you rely on your item build, and since if you rely on mana, you're VERY likely to have at least 1 mana regen item (In this case. A Manamune.), then the very slight increase to your late regen, is completely useless, and actually hurts your early game.

The armor pen. Really helps with early game harassing.

The crit damage increase. Is pretty self explanatory.

While this IS the build I use. It's not the 100% order I always get them in.

I always start with a sapphire crystal, and two potions. Depending on how much money I have when I go back, I always get an avarice blade, and +1 boots. If I have enough, I'll get the second avarice blade along with it. After that, I get my cooldown boots, or tear. Depending on how my lane is going. If I'm constantly having to push back, and harass, then I'll grab my tear first, and cooldown boots second. If my lane's going fine, then the boots first, then the tear.

From there. I get 1 zeal, and depending on how things are going, I'll either get my second zeal, then sell a avarice blade for a vampiric scepter. or. get a vampiric scepter, then sell an avarice for my second zeal.

After that, it's a straight forward Manamune> Phantom dancer> Blood thirster> Phantom dancer. Again though. There have been times where I rush my manamune immidiately after my second zeal. It's really a judgement call on how the game's going, and what you need at the moment.

Why not get a Infinity edge? Honestly. I've never once found I needed it. With this build I always have so much damage output. That having a little more, while having to cut back in some other area, just never seemed worth it. As it is. I can 1v1 Xin's with ease with this set up, and we all know how annoying 1v1'ing a xin can be -_-. Don't get me wrong, I don't walk away unscathed. But I do walk away.

I always go parlay first, then put two levels into remove scruvvy. This, mixed with the mana regen I already have from runes/masteries. Will mean I can pretty much lane endlessly. Make sure to put at least one point in raise morale after the two in remove scurvy. One point is enough, but it will help when running away, or chasing. As well as allies with the same.

Aside from that, not much explanation is really required.

Flash: Because Gangplank has no real escapes, and you should always have an escape on a champion.

Exhaust: To help with ganks mainly. Can also save you if you're being chased by someone mean looking, and brandishing something sharp (I'm looking at you Xin.). Exhaust them, hit raise morale, and run for the hills!

Gangplank has a fantastic passive on his Q: Parlay. If you kill something with it, it gives you extra gold. Similar to Ashe's hawkshot bonus, only you get a lot more money with parlay. At max level, you'll be getting an extra 12 gold per parlay minion kill. So every time it's off cooldown while farming, make sure to last hit the minion with parlay. Doing this will give you a HUGE money advantage over everyone else.

This may seem like an obvious thing to do. But 99% of the gangplanks I see, don't do this, and they suffer because of it. The only reason not to do this, is because it's very mana hungry. But since we already have a butt ton of mana regen with our mansteries/runes. This isn't an issue.

To be good with gangpplank, you'll need one thing. Good judgement. What I mean by this, is knowing when to stand back, poking with your parlay, and when to actually jump in, and melee/parlay all up in their face. Don't get me wrong. Once this build is finished, there's very few times, when you can't just run into their team, and let for parlay/melee attacks, mixed with your life steal, destroy them, and keep you alive at the same time. But until the build is finished. You'll want to focus on poking with parlay, and waiting for an enemy to go off to the side or something like that, then run in and poop all over them.

Knowing when and where to use your ult is another thing that just takes time and experience to figure out. If you get into a team fight, fire your ult right in the middle of them. If you show up late to a fight, and the enemy are turtling back to their turret and/or base. Put it in front of them. Your ult has a slow proc, on top of doing decent damage. So this can give your team a nice opening to catch up and make some turtle soup out of them.

Another handy use of his ult. Is if, for example, your top lane turret is getting hit by two waves of minions at once. But no one can get there before it'll be destroyed. Simply fire your ult on them. It'll save your tower, and get you a lot of extra gold/experience.

Is this the best gangplank build ever? No. I've always said. The best build, is the one that wins the game for you. For me though. This build works for me 9/10 times. So this is the best build for me. Hopefully it will work well for you too.