Nami is very much a teamfight support thou, Pyke does have that win, win more, lose fall off gameplay inherent to most assassins. Also I subscribe to the idea that its a mistake to play him like most AD assassins cuz his QE not really that spam able his R is best saved for kills, so you don't get as much out of stacked lethality. Im doing Glacial augmentation for extra CC in lane and
as a early item. Get a stronger on demand slow after
is completed then combo it into hook/slow hit the stun , Auto for the rune slow, then leap in and Execute for extra team gold during ganks. good bit of CC and the camo W gives you pretty solid ability to set up for it. Oh offtopic but you can use his passive to check for wards as it wont heal you if ones near. I tend to roam and im not as worried about killing or 1v1 as most assassins. I play him to open a fight, then finish it.
I really like BOTRK as an item, its just one of the most cost effective options in the game for some extra damage to your autos with a decent activated and decent stats all around.