Hearthpwn

Seerspine Puffer is really efficient if you manage to activate its effect early on. It has a lot of synergy with the neutral card Intrepid Diver.

Druid of the Fin's second effect can prove a good activator, as it triggers right away and persists until it leaves the battlefield. It's great if you manage to activate both effects, as the Elusive option gives this minion the survability it needs. (Fandral Staghelm might be wild, but there will be a card in future expansions that will allow to trigger both options).

Mystic Coatl can allow you to build some degenerate combos, but it needs you to be diving, which usually requires you to spend mana if you want to do it in a consistent way.

Levantus has a really powerful effect, but its high cost keeps it for being broken, and it fits the Druid ungoing theme of tricky removals.

Druid of the Fin's tokens. As always, this Druid of the Whatever cards have a ton of them :_D

And this is Levantus' Hero Power.

Deepfin Tamer helps you to use your Hero Power without losing tempo. SmOrc shall return!

Coldlight Scavenger is similar to Menagerie Warden, except it's much cheaper but the effect is delayed.

Cycle of Life provides a way to refill your hand as Hunter. Keep in mind that if you activated Furl's effect, when a Murloc dies it will give you both a Murloc and a Beast.

Furl, the Feral Murloc allows you to create a full Murloc deck in Hunter, while still being able to activate the Beast synergy spells the class have. You might even add some aggro Beasts to the mix, as Scavenging Hiena. Also, it has a lot of synergy with the other cards, as it allows Deepfin Tamer to trigger by itself, Coldlight Scavenger to duplicate a valuable Murloc such as Murloc Warleader and Cycle of Life to do what I explained in its own section.

The original effect of Furl, the Feral Murloc also turned your Beasts into Murlocs, although it was a 5/5/2. However, I felt it was too good and I nerfed it to its current state.

Arcane Sentinel allows you to tempo out a medium-sized Taunt if you manage to cast several spells.

Dim Mana Flame shuffles a bigger spell in your deck that also shuffles a bigger spell. It has a lot of synergy with the Epic and Legendary cards.

Manasurge Recycler makes sure you never run out of spells, altough its effect might be detrimental if you overuse it. However, it's a great setup for Arcanium.

Arcanium, Infinite Mana helps you refill your hand with cheap spells that can be used to clear the board or to deal some face damage.

Dim Mana Fire's tokens. They draw a card because otherwise would be really bad in the late game (which is where you will probably get them, because shuffling is not the fastest mechanic in the game).

I struggled a lot to decide if I made Manasurge Recycler and Arcanium, Infinite Mana have synergy with (3-) or (2-) costed spells, as the former felt OP (with secrets and stuff) and the later really underwhelming. I decided to go with the OP option, however.

Sacred Seahorse can be really sticky if you manage to Dive, attack with it and then Dive a second time. This might be hard to pull, so I am considering buffing it to a 3/2 which already has Divine Shield.

Deepfin Pearlfinder can create some hard to remove Murlocs and buff their attack too, but you need to have a lot of them and use Prayer of the Seas.

Prayer of the Seas is obviously a great activator, if you have a full board. As I said, Paladin is the most aggresive diver.

Puff the Pious Dragon gives you a way to refill your hand outside of Divine Favour. It is also a pretty obscure reference :P

As I said, I am considering to make Sacred Seahorse a 3/3/2 that already starts with Divine Shield.

Also, in the original version, Deepfin Pearlfinder gave all your Murlocs +1/+1 every time you dived, but I thought it was pretty degenerate in combination with Prayer of the Seas. Also, in the previous version, it was a 4/3/3 that only gave a friendly Murloc +1/+2, but it was perceived as too weak.

Darkscale Illusionist benefits when the opponent plays minions with heavy effects, such as Ragnaros the Firelord.

Naga Siren is a Potion of Madness on a stick, altough it is RNG dependant. I am a bit concerned about this card, though.

Watershape Gem lets you copy valuable spells, such as removal and so. It can be dead in some matchups, however.

Lady Vashj has the Entomb effect with solid stats for the cost. You can drop her when you're about to remove a big target.

I am thinking of reducing Naga Siren's Health to 2 or 3, and makes her effect only land on minions. That way, she depends less on RNG, altough she depends more on board state.

Lady Vashj's effect may seem unfitting for the character, so there will be an animation that "drowns" minions affected by it.

Walk the Plank! is removal that gets cheaper. You can make powerful tempo plays with it, but you need a really big hand for that.

Crew Cook provides Rogue with some healing, as the class needs it to enable a Control playstyle.

Blackwater Cannoneer gives Rogue some AoE, which they desperately needed after Blade Flurry got destroyed.

Master Gunner Prix brings together both Rogue sub-themes in this expansion. She is the win condition of Control Pirate, altough a slow one (because playing a lot of weapons together might be pointless).

I am thinking of changing Crew Cook's effect so that it does not depends on your weapon, as it feels too similar to Leeching Poison. Maybe a simple "Restore 3 Health to your hero at the end of your turn"?

Also, I am thinking of swaping the cost (and stats accordingly) of Blackwater Cannoneer and Master Gunner Prix, as it doesn't make a lot of sense to have an AoE which is more expensive than a win condition, even if it's as slow as Prix.

Honorable mention here goes to the Neutral Booty Hunter, which is the fifth Rogue card of the expansion.

Flood Conjurer is a slightly smaller Firelands Portal that is not RNG-dependant and is 2 mana cheaper. It requires you to be diving, though.

Power of the Tides is similar to Volcanic Potion, with the added benefit of diving. It's the only dive card that cannot trigger more than once. However, it has great synergy with the next card in the list.

Deepfin Ritualist allows you to put an incredibly cheap 4/4 on the board after clearing it with Power of the Tides, completely reversing the tempo advantage your opponent might have. It fits the Shaman theme of dropping giant stuff for small amounts of Mana.

Shrgl the Tide Seer grants a super safe activator of Dive without spending mana in the following turns. She is pretty good combined with the Neutral Guardian of the Tides.

Demonic Inquisitor is somewhat similar to Vilespine Slayer, as it's a removal tool that doesn't loose tempo nor cards in hand. Its effect might be too convoluted for a Common card, and it's hard to keep track of the amount of minions you killed (although its text will change when it's in your hand so that it's not hard to do this).

Stormreaver Necromancer can generate a wall of Taunts that are weak to AoE, altough it wouldn't hurt the Warlock too much, because they will feed other effects.

Soul Giant is what all giants are: a huge body whose cost gets reduced. In this deck, its main purpose is baiting removal, so that you can play Avatar of Sargeras without much fear.

Avatar of Sargeras is a huge gamble. Sargeras the Mad Titan is an Elusive 10/10/10 with Taunt, so it's impressive on attack and defense, altough it's weak to Silence minions. Avatar of Sargeras, however, is also vulnerable to transform removals, so it's better to bait them with other big minions. Also, even if it's a Demon I don't think it would be broken with Demon Recruit effects, as you need to be in the late game to activate its effect.

Engine of Souls is the equivalent of Soul Giant of this set: a big body to bait removals. I'm not very fond on how out of control this card can get, as it might reach huge stats in some occasions. However, it feels more like a Common card that Demonic Inquisitor of Set #1. I also like the fact that it also baits Silences, which Soul Giant couldn't do.

Bloodreaver Necromancy is (obviously) the spell version of Bloodreaver Necromancer in Set #1. As Engine of Souls, it can get out of control easy, altough a bit less because it's capped on the board size.

Finally, this Demonic Inquisitor is a somewhat cool card, altough it doesn't fit the theme very well, and Warlock has never had Deathrattle synergy.

Skeletal Grunt is the token for Bloodreaver Necromancer of Set#1 and Bloodreaver Necromancy of Set #2. They appeared near the Tomb of Sargeras in Warcraft III.

Sargeras the Mad Titan is the token for Avatar of Sargeras.

As some of these effects require you to keep track of how many minions died, the card text would change during the battle in order to avoid the user's effort. Here are some examples:

So, the text presented in upper spoilers would only be displayed in the Collection browser. During battles, it would look like in this spoiler.

Myrmidon Trident is a solid weapon, as its 3 durability allow it to clear many minions. It's also one of the friendlier Dive activators that exist.

Dragon Turtle is a neat survability tool, as it's a nice Taunt for it's cost and can net you a lot of Armor if left unchecked.

Hammerhead Bloodseeker is another card that is comparable to Vilespine Slayer: it has a harder requirement, but has better stats and can repeat its effect. The damaged condition is a double edged sword, as it makes harder to trigger the effect but also lets you pick your target.

Royal Guard Essok is Baron Geddon on steroids, as it only damages enemy minions (allowing you to build a board) and does more damage, although it requires you to be diving. It's designed to be hard to counter without removal, as it continuously clears your opponent's board and also puts some face pressure on it.

Intrepid Diver gives you a solid way to activate Dive effects in turn two. As Dire Mole proved, a 1/1/3 is really sticky even without additional effects.

Booty Hunter is a weapon discover, because I think there aren't any in the game. Also, has a lot of synergy with the Rogue theme of the set, Control Pirates.

Abyssal Monstrosity is really straightforward: just a 4 mana 6/6, which can be really dangerous if you manage to Dive several turns in a row.

Inksprayer Octopus is a huge mana investment in order to gain permanent Dive (except against heavy AoE cards). It can be good in the more control-oriented Dive classes (Druid and specially Warrior)

Guardian of the Tides is a good card for gaining tempo in Paladin and Shaman.

Seaside Kidnapper can provide additional Dive activators, altough you depend on RNG. Originally, it was a 4/5/2 which had "Battlecry: Discover a card that dives."

Queen Azshara provides you a reliable (altough inefficient) way to activate your Dive effects, from the beginning of the game. She compensates this by having awful stats. It's also remarkable that she is not in the Seaside Kidnapper card pool (it would make it much worse; also, a Naga would never kidnap his Queen :P).

Admiral Proudmoore generates a lot of value if you let it go wild. And even if you deal with the Admiral right away, you will still need to kill the Battleship, as it also has high health and does also generate a lot of value. I received feedback against this card, so if a lot of you guys dislike it, I will change the effect.

Jinx, the Deepfin Patriarch grants Murloc decks a comeback mechanism, altough you need to have a deck filled with Murlocs in order for it to work. I am considering making it a 5 mana 3/4 (and maybe removing Taunt), because I don't like having 2 neutral legendaries with the same cost. I know, the effect would come much earlier, but I also think that a 3/4 for 5 is much worse than a 4/6 for 7.

Admiral Proudmoore's tokens.