Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
[NOTE: This guide ASSUMES you've played Gangplank with other builds (such as full crit, tankplank, etc) before you've tried this one. Basically, this guide ASSUMES you have some familiarity with Gangplank. This guide also ASSUMES you're decent in ranked.]
Before any bashing occurs, through looking at the item sequence you'd probably think this is impossible. However, you will eventually sell Philosopher's Stone and Berserker's Greaves. The potions should obviously be consumed by level 5-6.
You can sell Philosopher's at any time, but I recommend keeping it until you start building Trinity Force.
The purpose of this build is to gain experience fast, deny the enemy gold/levels, have decent hp in team fights late game (3.3k with items + Elixir), and also do good damage (even against tanks). You build a bit slower than regular gp's because of this, hence the reason you get both Philospher's AND Avarice (which is a Ghostblade component).
If you think the mp5 runes are completely unnecessary, sub them for cooldown reduction runes for faster deny and more ulting. Be warned that you will need more mana pots throughout the game, but if you don't mind this setback, then go for it.
Before you criticize this build, please understand that Gangplank can dramatically outlevel any enemy hero and the reason why is because of his ultimate and his deny. You can abuse gp's ultimate by ulting creeps that are pushing an open lane (as in, a lane with nobody controlling it) and gain the experience from killing them.
I've been level 16 in a game where the highest level on the enemy team was 11, and there were still people under level 11 at that time. It's mainly because they did nothing but go around the map and try to gank, well this build is also a counter to that. Not only can you outlevel team-gank groups, you can also stay safe and deny by your tower making it difficult for people to tower dive you.
To ensure that this build performs well, you must--
A) At the start of the game, stay near the Nexus where the creeps of your lane are spawning and deny the first two armored creeps. Don't deny the casters! You want the armored creeps to die first so the enemy can push to your tower easier.
B) When laned, deny the biggest creeps (armored if armored are the only big ones, or the tankers).
C) Obviously, don't auto-attack creeps unless they're by tower. This is a given to anyone with medium rank ratings, but it's very important with GP. I used to buy 1 health pot and 4 mana pots with a ward, but if you deny you really don't need the ward very often since you're tower hugging. This may be different in 1600+rating games, but most games under that rating mia people don't tower dive 1-2 people with full health.
D) Try to determine the enemy team's movements. If they're all laning and hardly ganking, it's okay to use your ult while a teammate needs to go back and buy stuff. This way, the exp isn't getting wasted and that lane isn't getting pushed. If they're mia most of the time, save your ult and repeat steps B and C and play safe. If they dive you be sure to ult on them and exhaust a carry near the eye of the ult. You may get a few kills, but you'll most likely die too.
E) Don't leave your lane (during laning phase) unless absolutely necessary (buying or to get a kill, dragon, baron, or whatever the team captain/you decide). It's important that you utilize your exp gain and deny to get ahead of the enemy. If your team of 4 is defending against 5 of the enemy team at mid at a tower and the both teams are of equal level (lets say everyone on the enemy team is lvl 11 and so is your team), your team should be FINE to defend the tower because that is what the tower is there for. People that think "Oh, if only gp was here to help us we would be fine" are probably noob because gp is a melee hero with a gun and you're not playing tankplank, so there is little you can do to fend off a team besides ult.
I'm now going to explain the game in terms of phases as opposed to early/late.
Laning Phase: I guess this is the phase that happens either pre-20 minutes or before 1 tower in each lane is pushed. Basically, this is the phase that everyone should be using to lane and gain experience. Obviously, gank-teams don't follow the laning phase rule, and your team might not either but if you know ahead of time that your team wont be utilizing laning phase you might not want to use the same runes (use crit dmg instead of exp+). Basically you should be going through steps A then repeat B-E listed above.
Pushing Phase: This is after the laning phase. Obviously, you have more freedom. You should have a few items, but this doesn't mean you'll be doing insane dmg. You're still mediocre. Be sure that while you and your team are pushing one lane, you cover the others with your ult if the enemy team is visible via wards. If they're nowhere to be seen, save your ult to counter them. Once you get Ghostblade, you'll be a bit more hefty in team fights. Basically, you can wipe out one or two people on your own by popping your ult on the enemy, then using ghostblade. Obviously use ghost to catch up to a target and exhaust if you need to (but it's preferred to use exhaust defensively if an AD carry is attacking you). Once you get Trinity Force and Last Whisper, tanks will be much much easier to take down. All other enemies will probably take chunks of damage from this combo.
I'm going to try to beat people to the punch with questions.
Q: Why not focus more on crit?
A: Notice that the runes aren't focused around crit. If you want to go critplank, you'd probably want the runes for it. This build isn't for critting, it's for having some team-fight viability and longevity, as well as some deny to gain an edge against the enemy.
Q: Why no LL?
A: Honestly, if the enemy team has NO TANKS then maybe sub Last Whisper for a LL item of your choice. I won't bother choosing. There are several choices that are good with Gangplank.
Q: Why Frozen Mallet?
A: HP, damage, and the effect applies even with parley. You can open with a parley, then ghost/ghostblade to the enemy and wreck them (you might not even need to ghostblade or ghost, you could Boost Morale on a nearby creep and catch up to them).
Q: I don't like this build!
A: Then try the others. This is a specialized build that prioritizes getting an edge on the enemy in terms of levels and having good end-game team viability.
Q: Why Trinity Force? Don't you have to activate it THEN use it?
A: Actually, the moment you use Parley on someone two things happen. First the server understands that you have made a request to use a skill, so Trinity Force procs. Fortunately, the delay between the request and the landing-hit is so long that the effect applies on the same Parley you've just used. So, Trinity Force's increased damage bonus effect applies to Parley.
Q: Why bother with Ghostblade?
A: Ghostblade is a REALLY good item that does so many good things for Gangplank such as giving him a much higher attack speed, movement speed, cd reduction for abilities AND armor penetration... as well as damage and crit! It is the PERFECT item for Gangplank. In fact, if you want to build Ghostblade before Infinity Edge, by all means do so but keep in mind you wont get the most ouf if it without more damage and slightly more attack speed.
If I've missed anything please let it be known. In addition, please do ask questions so long as they aren't ones that were already asked.