This is my personal gangplank build. It focus on the early game farming and harassment but after some items goes into a carry style. As soon as the bloodthirster is finished youre able to take most champions 1v1 if your thinking smart. The last items is always picked based on the other team. Sometimes its items like Madreds and anoter phantom but its most common for me to buy a defensive item like Banshee or maybe guardian.

Youre role in teamfights is to wait for the inital ulties and then flash in to clean up the rest. U want to use the confusion to get some quick kills and pick of some of the opponents dps/casters. Dont use your ulti at the start but wait until u see someone important too slow.
The new remake makes it very nice to stop ppl from getting away.

Dont be afraid to spam abilities when u got the Philosopher stone. It gives amazing lane sustainability. The trick is to get as much minions as u can with Parrrley. Dont harras a champion u cant kill like rammus or malphite but use the parrley on minions instead for the increased gold. In the later stages of the game parrrley will be able to 3-4 shot a dps so dont be afraid to go into a fight. Make them wanna buy a banshee.

The early game is all about the farm. 3 gold items gives u 15 gold per 5 sec which adds up to 180 extra gold per minute. U want to have the items as long as u can. I usally sells my avarice blade when i need room for the brutalizer. The philosopher stone can u sell when u need the money or the item slot.