The deck is pretty straight forward, just abuse the totem and murloc synergy that Shaman has with only Standard cards in case you don't have a good Wild collection.
0 mana totem buffs are pretty good, Axe is pretty good, Reflection is nutty and Eys'or is pretty good, I don't think you need an explanation as of why. Argent Squire is simply a great target for both Reflection and Toxfin. Angler is just free value that your opponent has to remove ASAP. The rest of the cards are very self explanatory, either buffs or cards that work great with buffs.
The 2 cards I've seen no one else running are Lightning Breath which is a 3 mana Flamestrike in most scenarios and can end the game on the spot and then Dragonmaw Poacher which is always a 4 mana 8/8 with rush .
For mulligan always keep Squire, Custodian, Reflection, Eys'or and Poacher. On coin you can also keep Angler and Breath. You can also keep Crabrider if you already have Reflection cause turn 2 rider into turn 3 reflection is a pretty strong card. You could also run 2x Hungry Crab instead of the 1 Storm's Wrath and maybe 1 Captain/ Seer cause it's a 1 mana kill anything but I just don't have it on my EU account but it's definitely a better inclusion.