Building Manamune on Gangplank?
I've been playing some ranked with Gangplank (I'm Gold 4 so it's slightly creditable) and my first item recently has always been Manamune. It provides good damage as well as all the mana you need. Afterward I build into a Black Cleaver and destroy everyone. Usually after I build these 2 items I decide if I want to go tanky or damage, if I want more damage I always go Tiamat because Hydras really good on him. Go Spirit or Randiuns if you wanna be tanky, either way you're going to be dealing damage.
Tell me what you think of the build
P.S. My runes are 9 attack marks, 5 seals of scaling health, 4 seals of armor, 6 CDR Glyphs, 3 Magic Resist Glyphs, 3 AD Quints. Masteries are 21/9/0
Also these are actually my new updated runes/masteries. In testing I had tankier runes and went 9/21/0 but I've decided to try more ad thinking it will be better.