I created this deck out of a desire to see midrange murloc work for the shaman class instead of just a plain aggro murloc. I've tested a number of cards (and will continue to) and these are the ones that seem to be fitting together the best. So far I've had great success (~70% win rate) but most of my games have been unranked or between rank 16-18. I've been able to beat numerous popular archetypes (control warrior, zoo, handlock, demonlock, ramp druid, tempo mage, miracle rogue, midrange priest) and I hope to continue to do so.
Early game you want to control the board instead of just rushing face with your murlocs. Don't worry about flooding the board with murlocs, instead focus on making efficient plays and keeping key cards in your hand for good combos. If you can, drop a Whirling Zap-o-matic T1 with coin or T2. If your opponent has a 2 damage minion down already, don't waste your card, just wait until you have a taunt up to play it. There's no shame in using totems, removal and Far Sight early game instead of filling the board. Lightning Storm and Sludge Belcher can help you regain the board when the time is right.
The midgame is all about keeping the enemy board clear and keeping your own murlocs and minions alive. I try to combo Murloc Warleader with Coldlight Seer to provide two durable murlocs for 6 mana. Sludge Belcher is a fantastic way to keep your minions safe from minion threats and Loatheb is great at preventing AOE wipes. A T7 Neptulon with minions already on the board is amazing because your enemy will have to choose between dealing with your big threat or dealing with the other smaller threats.
Late game is closed out through the use of buffed murlocs, Neptulon, Al'Akir and Crackle (which has finished a ton of games for me). Unlike decks like freeze mage and control warrior, you'll likely be putting in face damage over the course of the match so you won't need some wombo combo like Alexstrasza or Grommash Hellscream.
Combos and Plays
Whirling Zap-o-matic: Insane early damage. I know this is a midrange deck but if you can coin one of these out T1, drop one T2, and drop a Flametongue Totem between the two T3 and throw down a Rockbiter Weapon on one of them, you can do 32 damage in the first three turns. Highly unlikely? Yes. Awesome? Definitely. Regardless, left alone it's 6 damage to their face. Mages can't ping them like they can with a number of early murlocs so this sucker ended up giving me 18 damage in a mage matchup.
Al'Akir the Windlord: Pretty much everyone knows about the power of the windlord plus Rockbiter Weapon or Flametongue Totem, dealing 12 or 10 damage to seal a game or put someone within Crackle range.
Murloc Surprise: Murloc Warleader + Old Murk-Eye + Coldlight Seer gives you a 3/5, 6/6 with charge, and 4/4 for ten mana. These three cards are the most powerful murlocs in my opinion and should generally be used in conjunction to increase survivability. There's nothing wrong with dropping them earlier if it's a good tempo move, but be careful with how you use your murlocs.
Siltfin Spiritwalker: This murloc is nice because it's got more health than the average murloc, allowing it to stay around for awhile. It's a nice drop when you know you have to sacrifice a murloc or two and if buffed by Coldlight Seer acts as Flamestrike insurance since it will most likely survive and give you cards for all the sacrificed fish.
Vitality Totem: A fantastic new addition from GvG. Having three health lets it survive a number of spells and minions. It's a guaranteed heal for 4 and it also alleviates at least 3 damage (unless killed through aoe) from face, making it a steal of a deal at 2 mana. The downside to the card is that it doesn't do anything really to improve your board situation so it's more of an aggro tech card.
Taunts: The five taunt options in this deck (Sludge Belcher x2, Defender of Argus, Al'Akir the Windlord, Feral Spirit and Stoneclaw Totem) are integral for keeping key minions alive. The most important minions to protect in this deck are arguably Whirling Zap-o-matic, Vitality Totem, Flametongue Totem, Murloc Warleader and Siltfin Spiritwalker. Don't just throw down taunts for no reason (except with hero power). Make sure that you have them out to protect an already placed or upcoming powerful minion.
Far Sight: Most people hate on this card but it works well to thin your deck and provide powerful cards for cheap. T3 Far Sight can net you a 2 mana Sludge Belcher to play in conjunction with a Whirling Zap-o-matic T4. A Lightning Storm isn't all that useful on T3 most of the time, but snagging a free one for T4 or T5 lets you add to the board while clearing the enemy's multiple small minions all at the price of giving up your T3 play. Of course, there's a 1/3 chance (about) that you'll get a card that is under value, but that's the risk you run with it. If you don't like it, feel free to drop it but I quite enjoy it.
Loatheb: Combo him in the same turn as a bunch of murlocs and you're likely to see them survive until the next turn where they can be combo'd with other murlocs.
Cards I'm debating including
Azure Drake: A number of five drops already but helps with card draw which is nice.
Jeeves: More for aggro but if I feel that card draw is way too low this might be an option.
Harvest Golem: Can help with board control but takes away from the murloc synergy.
Fire Elemental: Good damage and decent control. A bit mana heavy considering it can get overrun by aggro and might not do enough against control so I'm not entirely sold on it.
Bloodlust: Was in my initial iteration of the deck. It won me a game against a druid and gave me a nice push against a warrior but I found it to ultimately be a dead card in most situations.
Please leave comments. I would love feedback on this deck. This is the first I've seen of effective midrange murloc and I want to see it be a viable ladder option.