Gangplank is a legendary pirate, one of the toughest champions to perfect, but it's very rewarding when you master it. He's one of the few champions who can adapt to most match-ups by playing passive or agressive and who can have several variations on his build and playstyle.

With a great split push potential and a machine of destruction in teamfights, GP forces you to choose the right path depending on the enemy composition.
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GP top depends way too much on both junglers playstyles and the jungler matchup, i.e., incoming ganks and camps on the way. Since most matchups are more explosive, with more engage, you usually have to delay your Trinity Force to build Corrupting Potion, Doran's Blade/ Doran's Shield and boots (~2k), and you will need to go tankish since the midlaner will most likely be a damage dealer.

GP mid is way safer, with the disadvantage of losing the push in earlier levels for agressive mages like Ahri, Azir and Orianna. You can prioritize damage and CDR in most matchups though, which makes GP a team fight god if you can hit good barrel combos.