I used to play greyjoy much more frequently back when Kings of Salt and Rock was legal, and decided to take another stab at it. This deck is on the larger side (I like to keep them no larger than 62-63 cards), mostly because I wanted to playtest it a few times and cut back based on the results.

Agenda:
Knights of the Hollow Hill

Plots:
At the Gates
Blocade
Rise of the Kraken
Fury of the Kraken
Retaliation!
Take them by Surprise
Valar Morghulis

Characters:
Nute the Barber (defenders of the north cycle) x1
Ambitious Oarsman (brotherhood cycle) x3
Motley Crewman (brotherhood cycle) x3
Victarion Greyjoy (KotS)
Salt Wife (clash of arms) x3
Bloodthirsty Crew (brotherhood cycle) x3
First Mate (clash of arms)
Baelor Blacktyde (maester cycle)
Seaside Urchin (kings landing) x2
Harbor Thug (kings landing) x2
Dagmer CLeftjaw (KotS)
Asha Greyjoy (kots)
Wex Pyke (kots)
Balon Greyjoy (kots)
Maester Wendamyr x2
Tarle the Thrice-Drowned
Euron Crow's Eye (brotherhood) x2

Locations:
Training Vessel (maesters cycle) x3
Sunset Sea x3
Scouting Vessel x3
Refurbished Hulk (brotherhood cycle) x2
Fishmonger's Square (King's Landing)
Iron Island Fiefdoms x3
Bloody Keep x2
Longship Silence (brotherhood)
Gatehouse
Seastone Chair (defenders)


Attachments:
Kraken Tattoo (kings landing) x2
Support of Saltcliffe (maesters) x3
Driftwood Crown (brotherhood) x3


Events:
Called to Arms (maesters) x3
River Raid (botherhood) x2
We Take Westeros! (brotherhood) x2
Distinct Mastery (core) x2
Assertion of Might (kots)

my initial thoughts after putting this together is I am trying to "do too much". My focus was going to be on the raiding discard theme, coupled with the saltcliffe and krakten tattoo attachments as strength pumps and standing tech. The crowns coupled nicely with the distinct mastery, and the assertion of mights for an large power grab, and could also be used to trigger the seastone chair.

Plot wise, I threw blocade in to counter the lack of a setup phase due to the agenda, playing it first turn to give me a little bit of building room while ideally denying resources to the other players. I almost think I prefer fear of winter, but am running fury. At the gates allows me to drop Wendamyr right into play, giving me saves early and often. The salt wives are secondary saves.

I'm thinking the best way to improve this is to abandon the sub-theme with the chair, remove the crowns and distinct mastery and possibly add another fishmonger's square.

Suggestions?

I ran "raiding" as a subtheme for a while, and it's not quite fleshed out yet; maybe only 1 or 2 cards away, but not quite there right now. I think the general consensus on these forums is "decking your opponent is all well and good, but it doesn't win you the game." I'll be interested to see if anyone can put together something using the as yet unreleased Brass Link. Brass Link + Support of Saltcliffe is going to be painful once the Maester has a few chains on him.
I would definitely add at least 1x LIV since it is one of GJs only *reliable* draw mechanics; I would dump the Training Vessels to fit 2-3 LIV in since TV only works with Raiders and only discards one card if you win the challenge. I also think Fishmonger's Square is much more reliable if you are using 3x Frostfang Peaks since you dont need to win a challenge or anything to discard your opponent's deck, and you'll get to draw off of it before Marshalling. And of course those are twice as efficient when you are using Winter, which is helpful in a raiding theme since cutting their income slows down your opponent so you get more time to deck them. In fact, I think 3x Frostfang + Winter is probably the best way to deck them no matter how you put the deck together; get a Motley Crewman or two out and they'll really start losing cards quickly.
I don't think the first turn Blockade is a good idea; your opponent got to drop 5 gold worth of characters and locations in setup and then draw back up, which means they are far more likely to have Seas, Streets, and other discount locations than you are, so you are giving yourself 2 gold and them 0, but they already have better board position anyway so it sounds like you're only hurting yourself.
I agree you may be trying to "do too much" - without a setup it'll probably be difficult to get multi-card combos going unless you have Lanni or Martell-like draw mechanics.
Also, you can't use a Gatehouse if you are using KotHH.