Deck Overview

Murloc Shaman has been a interesting option ever since Unite the Murlocs came out way back in Journey to Un'goro. While that quest's time may have passed, we can still have some fun in standard thanks to a new shaman murloc: Underbelly Angler. Who needs Megafin when we'll never run out of fuel anyway? Combined with the snowballing potential of Murloc Tidecaller and Coldlight Seer, we've got a very powerful aggro deck.

Our goal is to use all of our mana in the first several turns to swarm the board with murlocs and buff them up with Grimscale Oracle and Coldlight [Hearthstone Card (Seer) Not Found]. We then either end the game quickly with Bloodlust or win a little later by running our opponent out of removals (thanks Underbelly Angler).

Mulligan

Always keep: Murloc Tidecaller, Sludge Slurper, Underbelly Angler

If you have at least one of the 3 above, you should also keep Coldlight Seer

Matchups

Against aggressive decks, we HAVE to play something turn 1. Preferably something sticky like Murmy or a coined Underbelly Angler because as soon as they gain full control of the board we're going to be in a very bad spot. You should be able to get [cardMogue Fleshaper out pretty early, so use him and Bluegill Warrior to maintain board presence. The best case scenario is that we just snowball with a powerful minion on turn 1, get value off of that minion turn 2, and then secure the board with either Coldlight Seer, Soul of the Murloc, or Feral Spirit.

Against control, it's important to keep in mind what clears the opponent has. For example: if you're against Quest Warlock, they're most likely going to have Hellfire on turn 4, or turn 3 if they have the coin. So either make your minions clear-resistant with one of your buff cards, or make it as awkward as possible for them to clear by only playing a few minions. The last thing we want is to put all of our minions on the board and then have them all removed by a single clear. It's tough to win after they get their powerful plays online, so don't be afraid to play more aggressively if you have to. Control will always out-value us in the long run, so try to end the game early. 

Improving the Deck - Card Swaps

Fortunately, Murloc Shaman can be greatly improved with only a few relatively cheap replacements.

Murloc Warleader - Essentially a 3 mana Bloodlust that comes with a 3/3 body. Fits in perfectly with the rest of our deck, so if you have them swap with the [Hearthstone Card (Mogue Fleshshaper) Not Found]s.

Scargil - Absolutely insane with Underbelly Angler, and it lets us cheat out our higher cost murlocs too. Definitely put him in over a Feral Spirit.

Nightmare Amalgam - He might not look impressive, but he has a pretty solid statline for a murloc and is pretty difficult to remove on turn 3, making him a prime candidate for your various buff cards. If you want to put one in, I'd take out a Feral Spirit.