This is a quick and diry guide on a way I have been playing gangplank that is fun and maddeningly hard to counter.
This takes advantage of the fact that mana regen runes except for quints were nerfed and that the doran shield is OP.
Basically this build accomplishes allowing you to out HP regen and out mana regen your opponent while you out-level them and pull them twords your tower for a gank. At that time you exhaust / cannon barrage them and roflstomp their corpse. There is no real counter except maybe kass.

Please read and try to understand this guide before voting. I welcome comments that are constructive. Please comment if you vote. Thanks.

Mana regen quints are OP. the yellow coule be switched for health / lvl, but I like out regening everyone and spamming denies.

Red crits give you most bang for your buck since parlays base damage can crit, assuming your damage / harass is mostly parrlay which is what I assume.

Blues get you to 15% CDR from runes and mastries which allows you to get ionian boots and a potion and have 40% CDR. More CDR = more parlays = more gold = more damage on parlays... well you get the point.

More mana regen, speed, imp exhaust. random pt in armor pen can be put in spell pen for slightly more impressive terribad damage cannonballs that are only there for the slow imho.

The xp mastery is important here as well, and the long buff duration is nice to have when you do get red.

Nothing really out of the ordinary here. Dorans shield is awesome when coupled with your mana regen and your self heal you will be able to outlane mundo with a pendant until he gets 6 then you will both be basically unkillable 1v1.

You want to get the crit before the damage of your IE components. This is contrary to like every other player except maybe trynd, but because of parlays base damage critting the crit % is way more gold efficient for upping parlays damage, which is all I care about. Rushing IE is no surprise, and Ionian boots are no surprise on GP, but you may be saying to yourself WTF, why did you get sheen noob. Sheen doesnt double parlay!

To that I answer: yes you are right, but casting parlay procs sheen and the proc ticks off on parlay connect. What does that mean mathematically?

Parlay before sheen = [parlay base damage (150 at lvl 5) + player damage (75 IE + 108 at lvl 18 = 183 or 223 with LW)] * crit mod if crit

Parlay after sheen = ][parlay base damage (150 at lvl 5) + player damage (75 IE + 108 at lvl 18 = 183 or 223 with LW)] * crit mod if crit] + player damage (75 IE + 108 at lvl 18 = 183 or 223 with LW)

Basically sheen gets you double your investment in damage on the IE and LW as well as doubles your base damage. This is more gold efficient after IE then damage or crit and increases viability of all damage bought afterwards.

Get top solo, deny two melee creeps on first wave deny 1 melee creep each wave, except on 3rd wave deny cannon creep.
Don't bother harassing with q. Just leave it unleveled and last hit with it until you are ready to harass at level 5 with lvl 3 q or 7 with level 4 q. When you are ready to switch to harass mode (lvl 5-7) do it after you have just leveled. The opponent will be underleveled and with the new changes to leveling health you can do serrious damage to them by using higher level specials agianst underleveled opponents.

Your lane hsould be prime for gank from lvl 1 on due to your deny. If your jungler does gank push your lane up so it will get hit by tower then b and buy. you will be back in lane before the creeps get to your tower and wont lose much xp.

You should now be setup for a good game. Just play smart and use your ult to split their team in teamfights. Attack squishes and use your passive on ppl like mundo. I may go mor einto mid and late game when I have time later.