I too really like the designs of these cards. I got some comments on them too.

Blindlight Oracle appears to be a better Worgen Infiltrator in Arena (which is quite good) and a great aggressive Murloc card in constructed.

Freebooter looks like it could open up some crazy scenarios, but the synergy of pirates and murlocs are difficult to balance.

I don't see Naga Myrmidon seeing constructed play, however.

Dread Pirate Ring is interesting. I'm still interested in where pirates/murlocs could go.

Faceless Sapper reminds me of Bomb Lobber in terms of the situations where it could get value. Interesting card design (RnG inspired) that probably wouldn't see much play.

Hydromancer is awesome. It does seem unbalanced, however, in a legitimate murloc deck. But the design is awesome.

Lady Vashj is an interesting mechanic. It may just end up being another minion to get removed in constructed decks though.

I really like Maws. Although the unique effects of these legendaries aren't as flashy as others, I think they could be okay. However, I think they need an extremely unique/useful effect to see play in this meta, and it doesn't feel like the sort of card Blizzard would implement. But Stranglethorn Tiger has always felt good both in Arena and (for a tiny bit) in Constructed, and Maws feels good like that. I think it should be a 4/7 though, definitely.

Felhunter is a very interesting card. No idea how it would pan out in Constructed, and it'd probably be very slightly below average in arena. There are some interesting things to note, such as it surviving a Sludge Belcher hit.

Mo'arg Doomsmith is a cool mechanic too. The variance on weapons in game also makes it difficult to judge. Imagine stuff like 8/3 or 7/3 Blood Fury though.

Warp Stalker could potentially be game-breaking as it creates 2 for 1s. It's an interesting design and I would also like to see where Blizzard could go with Enrage effects.

And so on. There's a giant amount of cards here, some more flashy than others. At the very least, the concepts are really intriguing. Ya did a beautiful job m8. :D