vikingincarnate

I really like the idea of Volrath's Shapeshifter in here.

I freaking love Leviathan decks. Which is why I run a very similar deck, with one difference in card choice that changed the entire shape of the deck:

Dream Halls.

Here's the link if you want to look at it:
http://www.mtgvault.com/vikingincarnate/decks/u-suddenly-leviathans/

With that adventure, I learned a few things that might help you out. Running Dream Halls is kind of a cop out, but it combos so nicely with Grozoth and Inkwells that it is silly. My deck is far from perfect, so I'm not suggesting that you cut out everything you have, it is just an alternate approach to a sea-creature deck. Above all, play the deck you want to play.

-Kracken Hatchlings are extremely flavorful and extremely cute. Almost as cute as Hedron Crabs, which are very flavorful, but not as good at blocking.
-Inkwells are silly good.
-Stormtide Leviathans demand removal when they hit the board.
-Brainstorm is great for topdeck fixing with Ula's Temple. T1 Ula, T2, untap, put Ula on the stack, Brainstorm with your open U, and put 2 creatures on top. Boom, 2/3 counters just like that.
-Spreading Seas. Works wonders because it ensures unblockability of your islandwalkers, draws you a card, and provides minor disruption. Definitely consider looking in to it.

Sure, not every player combos out, but many of them do. The thing about running a 'better' deck in EDH is that it increases your ability to deal with the 'EDH Masturbation Problem' where several players end up playing with themselves by having some kind of degenerate repetitive combo that takes 20 minutes at the end of every turn to net them 2 land, a creature, and I don't know, 3 spirit tokens (just an example, it's usually more efficient).

That is approximately zero fun.

They'll assume that you know every card they are playing, and that you won't be able to disrupt them. They sit and sorta haphazardly tap and mumble abilities, knowing that their combo is mostly complete, and because you understand everything they are doing, you're just going to let them play magic by themselves.

And, while you could just argue that one should avoid playing with such players, they do exist, and EDH is a format that caters to that style of play. Even if you don't want to deal with it, you should consider what it will take to do so, because it happens. Those people are rampant in the format.

I agree that you should enjoy your deck, but if you can enjoy your deck AND make it competitive, that's even better. (my opinion, of course. To each his or her own)

And I listed Planar Portal because it is a great reusable budget tutor. Fishes your general if he gets shuffled repeatedly. Is it absolutely necessary? No. Would it improve this deck? probably.

Aight, so here's the deal.

For EDH, there's a few things you need to decide before building your deck:
First, how much money do you want to spend
Second, do you want to depend on your general or do you want to use your general as a fun little 'bonus' in the deck.

The mentality of building a deck is significantly different. You need to balance offence and defense, disruption and control, and still maintain the ability to win under almost any circumstances.

The money thing:
You can instantly improve the land in this deck with true duals, and proper fetches, as well as ubiquitous in-color lands like Urborg, Tomb of Yawgmoth, cabal coffers, and Volrath's Stronghold. There are a TON of lands that you can put in your toolbox.

You can also run things like Jace TMS, Sol Ring, Force of Will, and Dark Confidant, Bitterblossom, all of which would greatly improve this deck.

Once you know how much you want to spend, you can start adding and subtracting to your cardlist to maintain your budget.

As your list stands, I think you'd benefit from a few things (and a lot more, I'll just list the big ones):
1- Drop the cluestones. In EDH they are LOLBAD. If you NEED the mana fixing, the signets are worlds better, but it's best to avoid them.
2- Need to get up to 99/1 for your card count
3- Your general benefits greatly from defense. Lightning Greaves, Swiftfoot Boots, even Darksteel Plate all would work well
4- Staples: Sol Ring, Skullclamp, Planar Portal, Demonic Tutor, Counterspell, Lightning Bolt, Vampiric Tutor, Damnation
5- Things that improve your general: Curiosity, Viridian Longbow (anything that turns him into a pinger), Pemmin's Aura, Lilliana's Caress, Megrim, Underworld Dreams, Yixlid Jailer, Grafdigger's Cage, Tormod's Crypt, Borjuka Bog.
You're fueling some player's graveyard, you NEED to carry graveyard hate
6- Other spells: You need more removal and disruption. Counterspells, red's direct damage, black's creature's removal. You are in 3 great colors for control, use them.
7- ramp. The aforementioned Sol Ring, Cabal Coffers, Magus of the Cabal, Dark Ritual, High Tide, etc. You need to up your speed, right now, you've got very few combos, and you're facing an uphill battle against decks that can combo out and hit huge amounts of mana while You're still sitting on yer bum with nothing but a Highborn Ghoul sitting on your field.

Every single one of your 99 cards must be selected for a reason, and have more than one use. ETB effects, activated abilities, and activated abilities that don't require tapping are all HUGE in EDH. To build a competitive EDH deck (or just even a functional one) the mentality you need to adopt needs to move away from: "put everything in-color that I want in a deck" to: "put the absolute best things I can in the deck"

It's just the format, but nobody will fault you for doing what you want, it's just hard to be competitive with just anything.

Slowly looking better. You'll have to play around with it a bit yet to figure out what works for you, your meta, and your budget.
The land base looks MUCH better, and you're starting to show some ramp.

I'd recommend that as you play games, make a list of things you wish you could do mid-game, or problems you encounter as you're playing, and then adjust your toolbox of cards to deal with these problems. That'll help you adjust for your meta, and see holes in your deck that need filling.

The best way to learn is by playing, but hopefully I've given you some ideas to help point you in the right direction. EDH can be an intimidating format to get in to, because it requires knowledge of a whole bunch of cards, and you routinely run in to players that just play cards and go in to what I call 'masturbation mode' and just play by themselves without telling you what's going on because they're comboing out.

Hope this helps!

So, I've been wanting to comment on this deck a while, I just haven't had the chance since leaving my all-too-short comment above.

First, you're missing a few EDH Staples, especially for G/B, so I'll assume you're on a budget. Money can make almost any deck better.

Let's start with the basic idea. You're trying to use your general's ability liberally, and that's great, but there's a few things you need to watch out for. First, your deck needs to be able to run without your general on the battlefield. Board wipes happen. Removal happens, shuffle and bounce happens. When this occurs, your deck still needs to be able to function, and I don't see that. You're missing a bunch of tools like recursion (E Witness) and ramp (gyre sage would be great in this deck, also Vorinclex, mana rocks etc. You're missing a ton).

That being said, you also need to be very careful, because your general is using a very finite resource. In a prolonged game with lots of graveyard hate (night soil, grafdigger, tormod, bog) you WILL start to run out of things in your graveyard. This can be a complete hozer for your current strategy, and is all the more reason to run B/G EDH Staples so your deck is more resilient. You're really focused on your general's strategy, but it is VERY easy to stop up your entire deck, and you need to be prepared for that.

Here's just some thoughts off the top of my head:
Gyre Sage
Buried Alive
Entomb
Lightning Greaves
Vorinclex
Sylvan Library
Rancor
Eternal Witness
Regrowth
Acidic Slime (this is a staple)
Blastoderm
Tormented Soul (sneak damge through)
Mana Reflection
Phyrexian Arena
Oracle of Mul Daya
Doubling Season
Liliana
Fleshbag Marauder
Sensi's Top
Jitte
Solemn Simulacrum
Beseech the Queen
Survival of the Fittest
Primal Growth
Maelstrom Pulse
Bonehoard
Abrupt Decay
Sol Ring
Vigor
Yav Elder
Umbra Stalker
Worldspine Wurm
Geth
Grave Titan (Prime Titan is banned)
Avatar of Woe
Living Death
Green Sun's Zenith
Forgotten Ancient
Nature's Resurgence
Mortivore

Land:
Dryad Arbor
Maze of ith
Vesuva
Urborg
Twilight Mire
Reflecting Pool
LLanowar Wastes
Bayou
Verdent Catacombs
Terramorphic Expanse
Overgrown Tomb
Treetop Village
Shizo
Agadeem
Cabal Coffers
Volrath's Stronghold
Oran-Rief

Some of these are 'staples' some of these are just really good fits in your deck. I don't think they'd all fit, by any means, but it should be a good list to get you started. Remember, you need a solid deck that is ENHANCED by your commander because your commander is so easy to completely stop up. You've got a good start, but it'll take some work and some playtesting to take it to the next level.

Good luck.

Please put the commander in the sideboard.

Edgewalker. But he's not modern legal.

Honor of the Pure >> Glorious charge

1, I agree with NinjaStyle, there should be a few more plains and swamps, maybe 2 more of each, max.

2, is Soulcatcher not enough owl for you?

Needs Devoted Druid and some form of proliferate, like contagion engine/clasp. If you cut the Black Sun and Grim Poppit, you should be able to fit some in.

But the Quilspike + Devoted combo is so broken and simple, it's a shame to not run it.

Where are your watelands?

Bummer, I always liked the idea from an iconic standpoint... the little pew-pew of spiders shooting web enchants has always been a pretty cool theme to me... meybe I make my own deck and find a way to break the idea...

You're missing the Arachnus combo, which is basically spider-tribal control. Add in 4x Arachnus spinners, and 4x arachnus web? turns your spiders into little shut-down machine guns.

Door of Destinies only triggers on cast, though, so your token machines won't add to the charge counters.

Don't build a Relentless Rats deck. That card inspires more bad decks than any other.

You're currently actually only 1 card away from an infinite combo:

Thornbite Staff

I hate to add in cards... but what about Arcanis?

Cards I'd consider dropping:
Reminisce,
Lay Bare,
Dizzy Spell (I don't see a CMC1 target worth it...)
Rewind
Crystal Ball
Merchant of Secrets
Voidwielder
Temporal Adept
Stern Proctor
Doubling Cube
Dissipate

Haakon is required to have the knights be played from the graveyard. Aluren only affects the hand. Even with just Aluren on the field, I do get to dump whatever I have in my hand though.

Lodestone Myr would give you a solid finisher, and You might want to consider running 4 palladiums so you can go infinite with the galvanizers with a fewer number of creatures (in case of wrath or shatterstorm or something) And, since you're going to have more mana than you know what to do with, consider adding Eldrazi? or something that can really burn through the mana like Masticore? The specimen seems to be broken.