If you can play this late game with a combo card, it could be decent (akin to playing Underbelly Angler + any old murloc on turn 10), providing you with a lot of cards worth of value for the cost of just 2.
However, the issue - like with Underbelly - is that rogue/murloc shaman doesn't typically want the game to go that long, and would rather finish things off sooner. If you were running this in some sort of combo rogue deck, why not just run miracle? Or the new deathrattles become 1/1 card with Mechathun and Unstable Element.
Provisionally bad. There are no combo cards cheaper than 2 mana combo cards and that means you need to wait till late game to draw something. Also, pool of combo cards includes crap like Cutthroat Buccaneer or Raiding Party in deck with no pirates.
I'd say we need at least two good 1 or 0 costed combo cards for this to work.