Hearthpwn

Gameplan

First off, this deck requires the Morgl shaman hero and Tinyfin Beach cardback to be at its most awesomest!

Lots of fun, basically play out your quest and spam murlocs. 3 reloads between the two Underbelly Anglers and Megafin. You might run out of cards fast, so either make sure you hold back some resources if you're expecting a board clear or play out asap to finish your quest in the midgame for a refill. It's best to always keep at least 1 murloc in hand in mid-to-late game in case you draw an Underbelly Angler.

Mulligan

Dream hand is usually: Murloc Tidecaller into Rockpool Hunter and Coldlight Seer or Call in the Finishers (on the coin) on turn 3. Biggest challenge is to get out Everyfin is Awesome asap. Earliest is turn 4 with 3 murlocs on board. Usually a win from there, but never play it unless you can attack and get value immediately.

Just try to play around things like Defile, Consecration, Hellfire, Arcane Flakmage and Fan of Knives as much as possible against control/slower decks and mulligan quest for early board if you think you're facing hard aggro matchups.

Substitutes

Even without the quest the tempo of this deck is insane. This deck easily makes it to rank 5 without the legendary murlocs. If you're missing those, justI add 2 x Primalfin Lookout.

If you are having too much trouble withMurloc Tastyfin being too slow, you can try 2 x Coldlight Oracle. Alternatively you can use the cheaper Ice Fishing, but I'd recommend using murlocs for draw since they also expedite your quest.

Fishflinger, Hench-Clan Hogsteed and Murmy are all also decent replacements if you're looking to make the deck more budget. The combination of Fishflinger and Coldlight Oracle can sometimes get you some nice mills too, but for me it always felt like I was giving my opponent way too many options.

Eater of Secrets is here for secret mages. Maelstrom Portal also works well in its place. You can add a second copy of Maelstrom Portal and drop Sir Finley Mrrgglton. He's just there for an extra token to remove early game enemies and a chance at getting warlock or hunter HP for draw or pressure. The portal would also be a nice way to get back board, as there are none at the moment.