Hearthpwn

Looks good, but I would remove Windfury for another Hex. Murlocs are weak until you go for a big push, and wasting them on removing big taunters (Sludge Beltcher, Druid of the Claw, Ironbark), or big minions puts you at a serious disadvantage. It's very easy for your opponent to trade 1 big creature for 2 of your murlocs.

I would also find room for 1 Lava Burst.

A couple Fire Elementals can really help too.

~~~

As for replacements, in case people don't have all the shaman cards:

Mana Tide Totem -> Gnomish Inventor (Basic Set, 2/4 body /w 'Battlecry: Draw one card' effect)

Siltfin Spiritwalker -> Cult Master (40 dust, 4/2 body with similar effect as Siltfin)

~~~

Just a quick tip I thought I'd throw out there. Don't play Coldlight Oracle until after your opponent has used all of their board clear spells. If your hand is running low (like 1-2 cards including oracle) then it is ok to do that as well, but only if you are losing field advantage.

Also, don't forget to Hero Ability every turn if possible. Those totems go a long way towards trading and finishing the game (/w bloodlust), as well as making your opponent use those board clear spells much sooner.